The BBC has said it is "urgently looking into the issues raised" by allegations made against the comedian Russell Brand after he was publicly accused of rape and sexual assault.
When asked if it would launch an investigation, the corporation said in a statement: "The documentary and associated reports contained serious allegations, spanning a number of years.
"Russell Brand worked on BBC radio programmes between 2006 and 2008 and we are urgently looking into the issues raised."
For the latest on this story, click here: Met Police responds to Russell Brand claims
It came after charity Trevi Women, which Brand supported through his own Stay Free Foundation, announced it was cutting ties with the presenter in light of the allegations.
Four women have accused Brand of sexual assaults between 2006 and 2013 while the comedian was at the height of his fame, in a joint investigation by The Sunday Times and Channel 4 Dispatches.
He denies all the allegations against him.
The allegations in full
In a post on Instagram, the Devon-based charity, which said Brand had offered his support last year through his Stay Free Foundation, wrote: "The media revelations have been difficult to process.
"But our priority remains and continues to be the safety and well-being of all women and girls now and in the future.
"We have ended our association with Russell Brand and the Stay Free Foundation."
According to his website, Brand's charity also supports Treasures Foundation, which provides accommodation to women with drug addictions in east London, and Friendly House, which runs similar services in Los Angeles.
Neither charity has publicly commented yet on the allegations against Brand. Sky News has contacted both for comment.
It comes as:
• Brand performed at a comedy show in London on Saturday
• Production company Banijay promised an "urgent investigation"
• Elon Musk and Andrew Tate reacted to the allegations against Brand
• The UK foreign secretary called for quicker responses to such claims
• A parliamentary committee said it would "closely monitor" the issue
• Amnesty International said claims were "shocking" but it received no complaints
Since the allegations were published on Saturday, politicians and celebrities have commented on the allegations.
The Commons Culture, Media and Sport Committee chair, Dame Caroline Dinenage, has promised that MPs will "closely monitoring" the response to the allegations against Brand.
Production company Banijay UK has also promised an "urgent investigation". The company owns Endermol, which produced The Channel 4 show Big Brother and its spin-offs, on which Brand worked at the time of some of the claims.
"In light of the very serious allegations relating to the alleged serious misconduct of Russell Brand while presenting shows produced by Endemol in 2004 and 2005, Banijay UK has launched an urgent internal investigation and will co-operate with any requests for information from broadcast partners and external agencies," the company said in a statement.
"We also encourage anybody who feels that they were affected by Brand's behaviour while working on these productions to contact us in confidence."
Amnesty International said no complaints or concerns were raised when Brand took part in its Secret Policeman's Ball fund-raising gigs in 2006 and in 2012.
But it urged women to come forward "if there is anything that they experienced at that time that is of concern."
The human rights group added in a statement: "We do not have an ongoing relationship with him.
"The allegations are shocking and distressing. Our thoughts are with the women involved."
'Certain things I can't discuss'
On Sunday night, Brand appeared live on stage in London hours after being publicly accused of rape and sexual assault, telling audience members "there were certain things he could not discuss"
The comedian turned up in a black Mercedes 46 minutes late to the sold-out gig at the Troubadour Wembley Park theatre, which was due to start at 7pm but did not begin until just after 8pm on Saturday.
The venue has a capacity of 2,000 and fans who had not bought valid tickets could be seen before the show begging front-of-house staff to let them in.
A video from inside his comedy gig on Saturday night showed him walking out on stage smiling and being met with cheers before telling the crowds: "Thank you, thank you, I love you."
Dressed in white trainers, grey jeans, a black jacket and sunglasses, the 48-year-old appeared to briefly address the allegations made against him before he began his set.
Audience members told the PA news agency Brand told them he hoped they would "appreciate" there were "certain things he could not discuss" during the show.
The set itself was shorter than the time crowds had waited for it to begin, and people could be seen leaving an hour and three minutes after it began.
Brand made a swift exit from the venue just before 9.40pm.
After the show, there was a mixed response from audience members to the allegations, with one telling Sky News: "I don't believe anything until it's... you need to see the evidence.
"I doubt it somehow. In my heart, I don't believe it."
Another said: "You stand by women, you know? Women stand by women.
"I'm not going to stand by a man, no matter how much you might like the things he says."
Brand has three more dates for his Bipolarisation live show tour, with his next a sell-out in Windsor, before appearances in Plymouth and Wolverhampton.
His alcohol-free wellness festival, Community, is also due to return in the summer next year.
'I feel like I'm being attacked'
Ahead of the publication of the claims, Brand, who has in recent years repositioned himself as a wellness guru and critic of the mainstream media, released a video entitled "So, This is Happening" in which he described the claims as "a litany of extremely egregious and aggressive attacks".
Brand said he "absolutely refutes" the accusations that "pertain to the time when I was working in the mainstream".
"As I've written about extensively in my books, I was very, very promiscuous," he said in the clip.
"I don't mind them using my books and my stand-up to talk about my promiscuous consensual conduct in the past. What I seriously refute are these very, very serious criminal allegations."
He added: "Also, it's worth mentioning that there are witnesses whose evidence directly contradicts the narrative that these two mainstream media outlets are trying to construct, apparently, in what seems to me to be a coordinated attack."
Signing off the clip, he said: "Now, I don't wanna get into this any further because of the serious nature of the allegations, but I feel like I'm being attacked and plainly they're working very closely together.
"We are obviously going to look into this matter 'cause it's very, very serious.
"In the meantime, I want you to stay close, stay awake, but more important than any of that, if you can, please stay free."
Musk, Tate and Gallacher react to accusations
Brand's video, posted on social media site X, formerly known as Twitter, received a response from the platform's owner, Elon Musk.
The billionaire wrote: "Of course. They don't like the competition."
TV star turned radio host, Kirsty Gallacher, who is the older sister of Brand's wife Laura, also shared the video on her Instagram story with a red love heart.
She later deleted the post.
Brand also received support from former Fox News host, Tucker Carlson, as well as Tristan Tate, the brother of controversial influencer Andrew Tate, who said he "did not believe one word of it".
Andrew Tate, meanwhile, re-shared a post on X which claimed Brand was getting the "Andrew Tate treatment".
The influencer is awaiting trial in Romania, charged with human trafficking, rape and forming an organised crime group.
Tate was indicted in June, along with his brother Tristan and two Romanian female suspects. They deny the allegations.
While the allegations have attracted the attention of major American public figures such as Mr Musk and Mr Carlson, they have yet to make as much impact in the US media as they have in the UK.
While NBC and the Washington Post have covered Brand's denials, alongside entertainment sites E! and TMZ, the story has featured lower down their websites, while the influential New York Times is yet to publish an article about the claims.
Cleverly calls for quick response to concerns
Meanwhile, the UK's foreign secretary, James Cleverly, spoke to Sky News about the dangers of "sharp differentials in power" following the allegations against Brand.
He did not comment specifically on the allegations but told Sunday Morning With Trevor Phillips: "We see that [sharp differentials in power] in the film industry, the entertainment industry and sadly, of course, we sit in the area that I work in terms of politics, where you have very, very significant power differentials, long working hours, people in that environment.
"Now, that is absolutely no excuse for individual misconduct and people have to take responsibility for their own conduct.
"In those environments, I think institutionally we need to be particularly vigilant.
"We need to make sure that we are going out of our way to protect the people that have less power than those around them.
"We need to respond to their concerns very, very quickly when they are highlighted."
'Open secret on comedy circuit'
Ayesha Hazarika, a broadcaster and former Labour adviser, told the same show about her own experience of working with Brand.
She said: "I was on the comedy circuit around the same time as Russell Brand, I gigged with Russell Brand, I went on a number of his shows and it was an open secret in the world of comedy for a long time that his behaviour made a lot of women feel deeply, deeply uncomfortable.
"Lots of female comedians talked about this behind the scenes but they didn't have the power to do anything about it.
"We see that story time and time again, whether it is researchers in parliament, young producers in TV and broadcasting.
"We have to have a situation where we believe people and we have a culture where if people do come forward they are taken seriously."
BBC and Channel 4 respond to claims
In response to the joint investigation, a BBC spokesperson said: "Russell Brand worked for a number of different organisations, of which the BBC was one.
"As is well known, Russell Brand left the BBC after a serious editorial breach in 2008 - as did the then controller of Radio 2.
"The circumstances of the breach were reviewed in detail at the time. We hope that demonstrates that the BBC takes issues seriously and is prepared to act.
"Indeed, the BBC has, over successive years, evolved its approach to how it manages talent and how it deals with complaints or issues raised.
"We will always listen to people if they come forward with any concerns, on any issue related to any individual working at the BBC, past or present."
Channel 4 said it was "appalled to learn of these deeply troubling allegations, including behaviour alleged to have taken place on programmes made for Channel 4 between 2004 and 2007".
The broadcaster added: "We are determined to understand the full nature of what went on.
"We have carried out extensive document searches and have found no evidence to suggest the alleged incidents were brought to the attention of Channel 4.
"We will continue to review this in light of any further information we receive, including the accounts of those affected individuals."
Channel 4 said it would be asking the production company who made the programmes "to investigate these allegations and report their findings properly and satisfactorily to us".