Environmental protesters inside the tunnel close to Euston station in London say they are at “tipping point” as conditions continue to deteriorate.
The activists have been camping underground since Tuesday night in a network of tunnels dug over several months beneath Euston Square.
The group is protesting against the construction of the high-speed rail link HS2 that will come into Euston.
But they are facing deteriorating conditions like a shortage of oxygen, internal tunnel collapses and an influx of liquid mud.
A person providing aid to the protesters said that "lives are vital" and called on police officers and eviction teams to stop their “evil tactics”.
Another activist said more than 60 calls have been made to emergency services.
The campaigners claim that someone is breaching the tunnels to pour water inside as a way to make it even less inhospitable.
A man outside the restricted Euston Gardens, who gave his name as "Dan", said: "We're very concerned about the people inside the tunnels. It's reaching a tipping point where we don't know how long they are going to be able to continue.
"We don't know how many are inside, we're trying to fetch them power bars, water and nuts to make it through this.
"What the police are doing is disgusting. Lives are at risk. We need to make sure that the people inside the tunnels are safe by any means necessary.
"They should give us full access to the tunnels to make sure they have the things they need."
A woman who gave her name as Lou said: "I'm trying right now to speak to officers to make sure their requests are being granted.
"There's been reports of water coming through. There's been debris falling on them. There's a lack of oxygen.
"I've been trying to speak to somebody and see what can be done to help them, but it's falling on deaf ears."
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Another environmental protester, who gave her name as Eon, said: "We're throwing food and power banks over to them.
"That's what they need right now. We need to stay in touch with the people inside the tunnels. They're not doing very well at all. There's water coming inside the tunnels.
"We know by now this is not rainwater. We know that the water coming in is very clean, so it can't be rainwater. I don't know who's doing it, it must be someone who does not want us here.
"When calls were made to emergency services, consequentially two hours later it stopped. So it didn't matter whether it was raining or not.
"I know there's been around 60 calls to emergency services so far as it's very dangerous inside the tunnels right now.
"Typically we would use drones to get food and power banks to the people in towers but we are unable to do the same thing for the people in the tunnels.
"Police are abusing the COVID restrictions. It's evil tactics. They arrested me as well but could never find out who I was because they couldn't find my ID. After 32 hours, they had to let me go.
"They were threatening me with six months in prison, but the judge let me go with no fine, no prison time, nothing.
"If you stay silent, that's the best way. HS2 is destroying a lot of nature. There is already transport from London to Birmingham.
"It costs every person in this country £6,000. I don't know whether everyone is willing to spend £6,000 for some businessmen to get to Birmingham or London quicker. People are losing their homes. Animals are going to lose their habitats. It's not necessary."
The HS2 eviction team has denied putting the activists' lives at risk.
In a statement on Thursday, National Eviction Team, the HS2 contractors dealing with the eviction, said: "The National Eviction Team has been engaged to lawfully remove activists from Euston Gardens.
"In their attempts to delay their removal, unlawful occupiers have occupied a crudely dug tunnel on the land.
"Due to the activists' inexperience, they are exposing themselves to significant risk by being in the tunnel.
"They also increase the risk to the high court enforcement officers specialist tunnelling team, who have been engaged to safely remove them."
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