Tony Blair may be summonsed to appear before Commons inquiry into on the runs

Former British prime minister Tony Blair could be summoned to appear before a House of Commons inquiry into letters given to more than 200 Republicans telling them they were not wanted for offences in Northern Ireland.

The implicit warning was given by the speaker of the House of Commons, John Bercow, after he heard complaints from the chairman of the Commons' Northern Ireland Affairs Committee about Mr Blair's failure to agree a date so far, despite numerous efforts.

Saying that Mr Blair was "one of the most important witnesses" MPs wanted to meet, the chairman, Conservative MP Laurence Robertson said: "He has not refused to do so, but in effect he has by not offering any date. He has offered to submit written answers, which I am sure you will appreciate is totally unsatisfactory," said Mr Robertson, reflecting cross-party irritation on the committee.

Replying, Mr Bercow issued a thinly-veiled warning, telling Mr Robertson that the Northern Ireland committee had powers to summon witnesses, “but I hope it will be possible to resolve the issue without recourse to that”.

Last night, a spokesperson for Mr Blair said his office is “in ongoing correspondence with Mr Robertson about the committee’s request, given that he has refused to accept written evidence”.

The decision to tell hundreds of republicans they were not wanted for prosecution was approved by Mr Blair during his time at 10 Downing Street, in the face of sustained demands from Sinn Féin.

The letters became controversial after the high court in London ruled that John Downey could not face trial on four charges that he murdered four British Army soldiers in the Hyde Park 1982 bombing because he had been – mistakenly – given a letter.

An inquiry headed by Lady Justice Hallett found that the on-the-runs letters scheme was "flawed, but not unlawful".