A hacking gang stole victims’ savings and tried to blackmail major companies including the maker of the best-selling Grand Theft Auto videogames, prosecutors claim.

Arion Kurtaj, 18, and a 17-year-old who cannot be named for legal reasons are accused of being “key players” in the LapsusS hacking group, a trial at Southwark Crown Court in London has heard.

The duo, aided by unknown associates, are alleged to have hacked the servers and data files of broadband provider BT and mobile operator EE before demanding a four million dollar ransom on August 1 2021.

Kurtaj is further accused of targeting transport giant Uber, financial technology firm Revolut and Rockstar Games, developer of the Grand Theft Auto series, in quick succession in September 2022, the court has heard.

He allegedly tried to blackmail Rockstar Games by threatening to “leak the stolen source code for the Grand Theft Auto sequel onto internet forums”, the indictment states.

Kurtaj and the youth are also accused of hacking software company Nvidia in February 2022 before threatening to “release Nvidia Corporation’s intellectual property on to the web” if it did not pay them.

In a closing speech to the jury on Monday, prosecutor Kevin Barry said: “The victims in this case, and they undoubtedly were victims, they were members of the public who suffered the SIM swap frauds and losses as a result of that.

“There were also big corporations who were targeted and attacked.

“It hasn’t been suggested by anyone that any of these attacks were just individuals out for larks and laughs.

“It’s perfectly plain from the evidence that those involved in the attacks were totally serious in this endeavour of hacking companies and stealing valuable data from those companies with the intention of profiting from that, sometimes on a huge scale, whether by blackmail or fraud.”

He said the jury has heard evidence from members of the public who had their data stolen during the BT/EE hack.

“They found their lives, some of them, turned upside down with accounts accessed and emptied of savings,” he said.

He said one man’s account on Coinbase, a cryptocurrency exchange platform, had £38,000 taken from it.

Mr Barry said “major corporations” were also targeted by the hacking gang and “enormous disruption and costs were suffered by them” as a result.

He added: “Make no mistake, in this case, members of the jury, that losses experienced by these companies were real, they were a direct consequence of the defendants’ actions and those of their associates.”

He added: “Any loss they suffered through activity like this will ultimately be passed on to their customers, people like us.”

He told jurors “each of the defendants has previous convictions for committing computer-enabled offences in the recent past”.

Psychiatrists have assessed Kurtaj as unfit to stand trial so the jury must decide whether he committed the acts alleged against him.

Kurtaj is charged with 12 offences, including six counts under the Computer Misuse Act, three counts of blackmail and two counts of fraud.

The youth is charged with two counts of blackmail, two counts of fraud and three counts under the Computer Misuse Act, relating to the BT/EE and Nvidia allegations.

He previously pleaded guilty to one offence under the Computer Misuse Act and one count of fraud.

The prosecutor is due to finish his speech on Tuesday.