Former prime minister Gordon Brown may have been the victim of email hacking by journalists, according to reports on a major police investigation.

Under Operation Tuleta, police are examining growing claims that computer hacking commissioned by journalists is as widespread a problem as phone hacking.

According to the Independent, claims are being investigated that Gordon Brown’s emails were hacked while he was Chancellor — a post he held between 1997 and 2007, after which he became prime minister. Brown has previously said his medical details were illegally accessed by journalists.

While Rupert Murdoch’s News International was initially highlighted as an alleged principal player in phone and computer hacking, other publishing houses have been drawn into the scandal. It is not clear which newspaper is said to have been involved in hacking Brown's emails.

Scotland Yard officers are understood to be paying particular attention to 20 PCs which may contain evidence that Brown and other high profile individuals had their emails hacked, the Independent reported.

Investigators are also examining evidence over whether emails from Brown’s former adviser, Derek Draper, were also illegally accessed.

Peter Hain, former Northern Ireland secretary, was last month advised by police that his computer may have been hacked.

Operation Tuleta is being run by eight officers entirely focused on the computer hacking claims.