MPS have demanded ministers name the almost 200 IRA terror suspects given a secret amnesty against prosecution as the First Minister of Northern Ireland threatened to resign over the issue.

The deals emerged following a court judgement that the main suspect in the Hyde Park bombing, in which four soldiers were killed in 1982, could not be tried.

A judge threw out the case against John Downey after it emerged he had a letter from Northern Irish police saying he was not wanted in relation to any crime.

Campaigners have demanded ministers reveal the names of the other suspects given reassurances they would not be prosecuted .

Yesterday David Cameron said it was "absolutely shocking" that Mr Downey would not be tried.

But he faced accusations of sanctioning "get out of jail free" letters by the Democratic Unionist Party MP Nigel Dodds.

Earlier Mr Dodds called on government ministers to "publish the number of letters that have been sent to these people — (and) the contents of these letters" .

No 10 have admitted that 38 similar letters have been sent to suspects since the Coalition Government came to power in 2010.

Northern Ireland's DUP First Minister Peter Robinson has threatened to resign, saying his party had been kept in the dark over the scheme.

Mr Robinson has now demanded a full judicial inquiry into the letters.

Northern Ireland Secretary Theresa Villiers has called on police to reflect on "the serious error".

President of the Association of Chief Police Officers Sir Hugh Orde, who was chief constable of Northern Ireland at the time of the error, said: "It is a matter of personal regret that a crucial oversight was made by a senior officer which resulted in erroneous information being sent to Mr Downey."

Labour former NI Secretary Peter Hain defended the letters saying they helped to bring "closure on the horror and violence" which afflicted Northern Ireland. .