Former Northern Ireland Secretary of State Peter Hain was told in 2006 John Downey was wanted for the 1982 Hyde Park bombing — even though the Donegal man later was given a letter saying he was not wanted by British police.

During an appearance before the House of Commons’ NI Affairs Committee today, Mr Hain repeatedly accused some MPs of displaying “a naivety” about the difficulties faced by those who were involved in trying to get Sinn Féin signed up for policing in 2007.

In February, the Central Criminal Court in London ruled Mr Downey could not be tried over the Hyde Park attack because he had got a letter even though it emerged that he was not wanted by the Metropolitan Police.

The decision to grant Mr Downey a letter led to fury in Northern Ireland and an inquiry by the Commons committee and a judicial one headed by Lady Justice Hallett, which is holding its evidence sessions in private.

The controversy has led to a blame-game between elements of the British civil service and between past and former officers of the Police Service of Northern Ireland over the quality of the checks that were made in Mr Downey's case before the letter was issued in July 2007.

In a witness statement for Mr Justice Sweeney, Mr Hain, who served in Belfast between 2005 and 2007, said he first became aware that Downey had got a letter when he was approached last year by Mr Downey's solicitor, Gareth Pierce.

Democratic Unionist MP Ian Paisley Jnr said the British Attorney General Peter Goldsmith had written to Mr Hain — itself a rare event, Mr Hain accepted — telling him Mr Downey faced questioning for murder and causing explosions.

Given that level of knowledge, Mr Paisley accused Mr Hain of “inadvertently perjuring” himself before Mr Justice Sweeney - a charge which led to angry demands from Mr Hain that the allegation be withdrawn.

Defending the letters, he once again denied that they were an amnesty, since the 200 Republican on the runs who received the letters were merely told whether they “were wanted or not, it was no more than that”.

He said he had never been involved in making decisions about the names of the people to be given the letters, but he made clear that the letters themselves were a crucial part of the jigsaw that led Sinn Féin to support policing in 2007.

“At no time was I aware of the names, or the timings, nor the nature of the assessments made. These were matters for police and law officers,” said the Labour MP, adding that such involvement by a politician would have been entirely improper.

Mr Hain was sharply critical of former PSNI chief superintendent Norman Baxter, saying that he found it “hard to understand” how Mr Baxter could not have passed on information Mr Downey was indeed wanted because there clearly were checks made.

Relations between the two are poor, following Mr Baxter’s “extraordinary, inflammatory and libellous” declaration to the Commons committee that Mr Hain’s statement to the court had seemed “almost to express glee” about the Hyde Park bombing.

“I take great offence, it was pejorative and untrue,” said Mr Hain, though the Conservative chairman of the committee, Laurence Robertson replied: “We have not felt it necessary to ask him to withdraw.”