Former prime minister Tony Blair could be called before a parliamentary inquiry to explain a 'secret' deal he made with Sinn Fein during the Irish peace process, the Sunday Telegraph reported.
The deal saw 200 letters of assurances sent to fugitives known as 'on-the-runs' telling them they were not wanted by the police in the UK.
However, it did not rule out future prosecutions if new evidence emerged.
MPs on the Northern Ireland Affairs Committee are investigating the collapse of the case against John Downey, who was wrongly assured he was not wanted, when in fact Metropolitan Police were looking for him in connection with the 1982 Hyde Park bombings.
The Committee may now seek Mr Blair to give evidence as his role in orchestrating the deal is coming under increasing scrutiny.
Tony Blair should be impeached for misleading the Commons on the eve of the Iraq war, the UK's most senior MP has said.
Father of the House Sir Peter Tapsell said backbench MPs should use their "ancient" powers to haul the former prime minister before Parliament.
Sir Peter, who first entered the Commons in 1959, was one of a handful of Conservative MPs to vote against the Iraq war in 2003.
He challenged David Cameron to act during Prime Minister's Questions today, but Mr Cameron failed to directly address the query.
Boris Johnson has launched a pointed personal attack on former prime minister Tony Blair over his claims that the current conflict in Iraq is not linked to the West's 2003 invasion.
In his Daily Telegraph column, Mr Johnson said Mr Blair had "finally gone mad" and his "unhinged" attempt to rewrite history is undermining arguments for Western intervention in Iraq.
"In discussing the disaster of modern Iraq he made assertions that are so jaw-droppingly and breathtakingly at variance with reality that he surely needs professional psychiatric help," the London Mayor added.
He said that by refusing to accept that the 2003 war was "a tragic mistake", "Blair is now undermining the very cause he advocates: the possibility of serious and effective intervention.
"Somebody needs to get on to Tony Blair and tell him to put a sock in it, or at least to accept the reality of the disaster he helped to engender. Then he might be worth hearing," Mr Johnson concluded.
A former British Ambassador to the United States has supported former Prime Minister Tony Blair's calls for the international community to look at a renewed military intervention in Iraq.
Sir Christopher Meyer told ITV News Britain does not want to "get caught in someone else's civil war", but said Iraq as an ally should be given "appropriate help".
ITV News Political Correspondent Romily Weeks reports:
Former Liberal Democrat leader Sir Ming Campbell criticised Tony Blair for the claims that lack of intervention in Syria, not the 2003 Iraq war, is to blame for rise of Islamist insurgents in Iraq.
"To suggest that this has nothing to do with the instability which we now see in Iraq in my view flies in the face of common sense," the veteran politician told ITV News.
Tony Blair has rejected claims that invading Iraq in 2003 is linked to current violent insurgency.
Ukip leader Nigel Farage dismissed Tony Blair as an "embarrassment" who should hold his tongue - and added he is opposed to Western military intervention in Iraq or Syria.
Mr Farage was commenting on the former PM's claims that lack of intervention in Syria is to blame for rise of Islamist insurgents in Iraq.
The Ukip leader said Mr Blair's "state of outright denial of the obvious consequences of his disastrous decision-making on Iraq is making increasingly uncomfortable viewing."
"In almost every country in which the West has intervened or even implied support for regime change, the situation has been made worse and not better," he said.
Former Prime Minister Tony Blair said that while there were "perfectly legitimate" debate about the role of the US/UK invasion of Iraq to topple Saddam in 2003, it was important to look at the events in Iraq in relation to the war in Syria.
Speaking in a pre-recorded interview on BBC1's Andrew Marr show, he said the single biggest worry for security forces in the UK and across Europe was the threat of returning jihadist fighters from Syria.
Former top diplomat and Britain's ambassador to the US during the Iraq war has rejected Tony Blair's claim that the violence in Iraq is linked to Syria and not the 2003 war in Iraq.
Sir Christopher Meyer, who was Britain's ambassador to the US from 1997 to 2003, said Mr Blair's decision to intervene in Iraq was naive and said the handling of the campaign against Saddam Hussein was "perhaps the most significant reason" for the sectarian violence now ripping through Iraq.
"There are many reasons for this disastrous state of affairs," he wrote in the Mail on Sunday.
"Perhaps the most significant is the decision taken more than 10 years ago by President George W Bush and Prime Minister Tony Blair to unseat Saddam Hussein without thinking through the consequences for Iraq of the dictator's removal."
Tony Blair has blamed the violent insurgency in Iraq on the "predictable and malign effect" of the West's failure to intervene in Syria and denied it is linked tot the West's invasion in 2003.
Tony Blair's essay 'Iraq, Syria and the Middle East' rejects claims that invading Iraq in 2003 is linked to current violent insurgency.Read the full story ›
Tony Blair has blamed violent insurgency in Iraq on the "predictable and malign effect" of the West's failure to intervene in Syria and denied it is linked tot the West's invasion in 2003.
In a renewed call for military action, the former prime minister rejected arguments that his decision to go to war with Iraq was behind the current violence as "bizarre".
In an eight-page essay on his website, he said that unless the international community was prepared to overcome public reluctance and confront the extremists "hard, with force", the consequences would be more serious still.
Mr Blair - now a Middle East peace envoy - said Iraq was "in mortal danger" but pinned the blame on the sectarianism of the Maliki government and the spread of Syria's brutal three-year civil war.