The group of Russian hackers allegedly behind one of the worst cyber bank frauds of the last decade was unmasked on Thursday, with its leader indicted in America and the full scale of purported crimes revealed in remarkable detail.

The Moscow-based unit was identified as Evil Corp and dubbed “the world’s most harmful cyber crime group” as British and American officials revealed the results of an investigation into the group and its activities that has lasted a decade.

Maksim Yakubets, 32, was accused of being the group’s leader and was indicted over two separate hacking schemes. A $5 million reward was announced by the US State Department for any information that leads to his arrest.

Customers of nearly 300 organisations in 43 different countries have been targeted by the group, with financial losses in UK alone assessed to be worth hundreds of millions of pounds.

Evil Corp was accused of ruthlessly exploiting online vulnerabilities, tricking people into clicking on internet links that would install viruses, scanning for bank account details and then creating wires transfers to “money mules” working with the hackers.

Victims ranged from small businesses and schools to individuals saving for retirement and even religious groups, including some Franciscan sisters in America who lost tens of thousands of dollars.

The US Treasury announced sanctions against 17 individuals linked to Evil Corps, including Yakubets, the baby-faced Russian alleged to have hidden behind the moniker ‘Aqua’ online whose image is now on “wanted by the FBI” posters. Seven entities were also sanctioned.

Yakubets was accused by the US Treasury of working with the Russian spying agency FSB in 2017, including “acquiring confidential documents through cyber-enabled means” for the Russian state. He was also said to have been trying to get a license to work on classified material with the FSB last year.

The claim raises questions about whether the Kremlin is turning a blind eye to notorious computers hackers in its capital, or even leaning on their expertise to support Russia’s nefarious online activities.

The group’s willingness to boast about the proceeds of their alleged criminality online, acting like “extravagant millionaires” according to one senior UK investigator, was said to have helped result in their unmasking.

Videos released by the UK’s National Crime Agency [NCA] featured alleged members of Evil Corp showing off their sports cars and holding up traffic in Moscow as pulled doughnuts in the middle of the street.

Other videos purported to show the hackers petting the group’s lion cub and mucking about on segways.

According to UK officials, Yakubets has a customized Lamborghini supercar with a personalised number plate that translates to ‘Thief’ and spent a quarter of a million pounds on his wedding.

The announcements were the work of a pain-staking investigation from officials at America’s Justice Department, FBI, State Department and Treasury as well as Britons at the NCA and Metropolitan Police.