Yakuza gangs are carrying out coronavirus-related fraud and have increased the price of street drugs as they struggle to make money during the pandemic, experts on Japanese organised crime have told Sky News.

COVID-19 has affected the operations of the centuries-old criminal network at a time when it was already fighting for its survival.

The yakuza, a collection of separate gangs much like the Italian-American mafia, has reportedly carried out humanitarian work during the crisis in an effort to improve its public image.

Japan's government has not imposed a nationwide lockdown but large numbers of the population, including yakuza members, have opted to stay indoors.

Members of the organised crime syndicate make their money through "shinogi" - a Japanese term which roughly translates as "hustle" - and includes illegal activities such as drug-dealing, prostitution, blackmail and protection rackets.

Jake Adelstein, a Tokyo-based investigative reporter who has been covering the yakuza for more than 25 years, told Sky News that younger members are having to find new ways to make enough money to pay up to their bosses each month.

He said: "Yakuza members, like everyone else, have decided to stay home.

"This means they can't collect their usual protection money from clubs, bars and dens of ill repute.

"One of the things they have been doing is selling high volumes of masks at high prices to small retail businesses.

"But it hasn't been very profitable for the gangs."

Mr Adelstein, who faced death threats from a yakuza boss while working as a crime reporter in Tokyo, believes the gangs are set to target members of the public, who are able to apply for 100,000 yen (£757.20) to help them through the pandemic.

He continued: "Companies are appearing online that say 'we will handle the complicated processing of these forms and compensate them for you if you just give us your personal information and bank account number'.

"And of course they'll just drain your account and not do anything for you."

Mr Adelstein said yakuza bosses are even considering whether to "suspend dues" from young members struggling to generate an income.

He said: "The gangs operate like franchises, where those lower down pay money up to more senior figures.

"The leaders have been considering not asking the younger members to cough up money each month, but this hasn't been decided yet."

Yakuza expert and author Tomohiko Suzuki told Sky News the gang members who have profited most during the coronavirus pandemic are drug dealers.

He said: "The public has been following the call for people to stay at home. The price of marijuana and stimulants have risen to nearly double in some areas since then.

"Drugs are ordered over the phone and delivered by car.

"Illegal brothels have always been illegal brothels. The gangs are still running those but no customers are coming."

Mr Adelstein said it is likely the yakuza will attempt to start loan sharking, where money is lent with unreasonably high rates of interest, but added most business owners will take advantage of a borrowing programme set up by the government instead.

The yakuza expert said many of the syndicate's senior members are elderly and have been "staying home and cowering" due to fears of catching the virus, which is more likely to be fatal in older patients or those with underlying health problems.

He added that some have been contacting each other using fax machines because the yakuza are "actually very behind with technology".

Mr Adelstein continued: "While they'll hire people to do corporate fraud and can work with virtual currency, the people at the top are very old school."

He added that many of the members are scared of getting the disease because being "felled by a tiny virus" would be seen as a sign of weakness in the "macho world of the yakuza".

Two of the network's biggest gangs, the Yamaguchi-gumi and the Kobe Yamaguchi-gumi, have been engaged in a turf war in recent years.

Hospitals may therefore refuse to take in patients with the yakuza's trademark garish tattoos for fear of being at the centre of an attack.

This has made gangsters even more keen to avoid catching the virus.

With yakuza gangs having faced a government and police crackdown, some members have reportedly offered to help those affected by the coronavirus crisis in an effort to win public support.

One gang offered to send its members to clean the coronavirus-hit Diamond Princess cruise ship which was docked at Yokohama in February, the Japanese news site News Post Seven reports.

The country's government is said to have refused the offer.

Gang members also distributed masks to kindergartens and pharmacies for free when they started disappearing from supermarket shelves, according to the Organised Crime and Corruption Project.

Yakuza members were some of the first on the ground and sent in truckloads of relief including food, water and blankets, after northeastern Japan was hit by the Tohuku earthquake and tsunami in 2011.

Sky News contacted the yakuza through its official website to ask what humanitarian work it had carried but during the outbreak, but the organised crime syndicate did not respond.

Mr Adelstein said the yakuza, which started in the 17th century, is now in "the worst position it has ever been in" as the government brings in laws to limit its activities.

He added that the amount of material the yakuza has to blackmail politicians is "not what it used to be".

Mr Adelstein said in a few years he will be "more of a historian" than a yakuza expert.

There are 22 major gangs in the syndicate at the moment, but overall membership is now below 10,000.

This is down from around 80,000 in 2010.