Former Secretary of State Peter Hain met with detectives in London yesterday over claims his computer was hacked during his time in Northern Ireland.
And it was claimed last night that police believe that former PSNI Chief Constable Sir Hugh Orde could also have been a News of the World hacking victim.
A spokesman for him last night declined to comment.
However, it is understood the allegations have been unearthed by a specialist Metropolitan Police team working for Operation Tuleta, which is examining computer hard drives seized from at least three private detectives used by News International.
“This is rapidly making the phone hacking allegations look tame,” said one source.
“Hacking into the emails of the Chief Constable is about as bad as it gets.”
Police are examining evidence suggesting that Peter Hain’s files, as well as those of senior civil servants and intelligence agents, were targeted by private detectives who may have been working for News International.
Foyle SDLP MP Mark Durkan, who worked with Mr Hain on the peace process, said: “Now we know Scotland Yard are thinking that this activity may even have extended into trying to engage in illegal subterfuge, into the conduct of ministers by penetrating the machinery, the technology of government.”
Peter Hain’s two-year stint in Northern Ireland, which ended in June 2007, was during one of the most critical phases of the peace process, which included the fall-out from the Northern Bank robbery and the murder of Robert McCartney outside a Belfast pub in 2005.
The recent revelation has now led to calls from several MPs who want to see the ongoing Leveson inquiry examining hacking in Northern Ireland.
DUP MP Ian Paisley Jnr has claimed his mobile phone was hacked when he was a junior minister in Belfast.
He has written to the Metropolitan Police and has called on the Leveson Inquiry to investigate.
The North Antrim MP said that he was “utterly convinced” his phone was hacked in 2008 when he was involved in planning-permission controversies which led to his resignation.