By Andrew Woodcock, Press Association
Tony Blair has denied that he authorised the security services to tap the phone of the late Ian Paisley when he was an MP.
Former deputy prime minister Lord Prescott claimed on Sunday that Mr Blair told him in 2005 that the security services had eavesdropped on the firebrand politician's calls.
The late Democratic Unionist Party leader's son, Ian Paisley Junior, has pledged to raise the issue in Parliament, branding any bugging of his father's phone "utterly disgraceful".
Mr Paisley Jr, now MP for Antrim North, said Lord Prescott's account had uncovered an "utterly disgraceful breach of the Wilson doctrine sanctioned by a government that would do anything for its own end".
He added: "This will be raised in Parliament on April 18. Did Prescott oppose Blair on this? All MPs' freedoms undermined by the action of Blair."
But Mr Blair's office insisted that the story was "wrong" and suggested that Lord Prescott's account may arise from a "confused" recollection of a discussion about the long-standing convention - known as the Wilson Doctrine - that MPs should not have their communications monitored.
A spokesman for the former prime minister said: "This story is wrong. No authorisation for the phone-tapping of a Member of Parliament was given during Mr Blair's time as Prime Minister.
"It may be a confused account of the discussion of the Wilson Doctrine in Cabinet - something which was public at the time - which dated back to the 60s."
Writing in his Sunday Mirror column, Lord Prescott said that he had been informed of the phone-tapping after the Interception of Communications Commissioner contacted Downing Street.
"Tony asked me to discuss the Wilson doctrine with the Speaker of the House of Commons. I never told him that an MP had been tapped or that it was Paisley," said the Labour peer, who served under Mr Blair from 1997-2007.
"Parliament was not informed and Paisley went on to become First Minister of Northern Ireland.
"I can only think that as the peace process was still a concern, mentioning the fact a leading loyalist politician had been tapped by Britain's security services in the past would not have helped."
The Sunday Mirror said Lord Prescott does not know when Mr Paisley's phone was tapped or whether MI5, MI6, police or the Army were responsible.
He approached then-Commons speaker Michael Martin to discuss how the Wilson doctrine was applied but did not mention it was prompted by what he had learned about Mr Paisley.
In March 2006, Mr Blair assured Parliament the Wilson doctrine would be maintained despite advice to scrap the policy.