The government has come under fire from an influential committee of MPs for its handling of prisoners at a Northern Ireland jail.

Downing Street was singled out for particular criticism, for blocking access by the Commons Northern Ireland affairs select committee to key officials when conducting its inquiry into the separation of loyalist and republican inmates at Maghaberry prison, near Lisburn in County Antrim.

Ministers agreed to a £14 million transformation of the jail, after inmates complained that it was not safe.

During the stand-off, republican prisoners smeared their cell walls with excrement, while loyalists on the outside attacked wardens' homes, a situation that escalated at the same time as the collapse of the Stormont assembly.

"Depressing" decision

Nevertheless, MPs described the decision as "profoundly depressing", and insisted that no more concessions be made amid fears that the prison could come under the control of paramilitaries.

"We believe that the separation of paramilitary prisoners at HMP Maghaberry was demanded by dissidents for political reasons and acceded to by the government for [other] political reasons," said the report published on Wednesday.

"We accept that the prevailing political conditions in Northern Ireland in the summer of 2003 placed the government in an extremely difficult position.

"Nonetheless we have to record our belief that the decision taken, as we see it, contrary to the balance of the facts and arguments presented to us, was a dangerous one, most especially for the public servants who will have to implement it and live with its consequences."

While the review team, headed by former Northern Ireland prison service chief John Steele, recommended separation, other factors came into the decision, the MPs concluded.

"While the minister, Jane Kennedy, did not assent to the proposition that a potential hunger strike was a factor in the review process, it seems to us to be the most plausible explanation for a decision which appears to be unsupported by the weight of the evidence presented."

Senior advisers unavailable

However, the committee admitted to uncertainty over why the government agreed to the demands of the inmates, partly due to their being unable to take evidence from key officials inside Number 10.

These are said to include chief of staff Jonathan Powell, who has played a considerable part in the Northern Ireland peace process since Labour came to power in 1997.

"Our examination of the full reasons which may have led to separation was, to some extent, hindered by current limitations on select committees' ability to question staff of Number 10 Downing Street," said the report.

"Following evidence from the minister that staff of Number 10, whom we are not able to question, had been in discussion with the Northern Ireland Office during the period of the protests, our concerns were expressed about this gap in accountability to the prime minister at a meeting of the liaison committee on February 3.

"We feel it is important to establish the full facts of such decisions and this can only be done by questioning the officials concerned at Number 10."

However, they welcomed the "sympathetic response" Tony Blair gave to the chairman of the Northern Ireland committee that he would look into the policy of not allowing officials to give evidence.