BBC's Carole Walker: "The issue of prisoner releases is a critical one for all parties to the agreement"

The Northern Ireland (Sentences) Bill will pave the way for the release of 400 prisoners in the province over two years.

The scheme formed a central tenet of the Good Friday Agreement which sets out a new future for Northern Ireland.

But it also angered many unionists in the community and was a significant reason for many of them voting against the accord in last month's referendum.

Mo Mowlam briefed Opposition members about the Bill

The full details governing early releases have remained a closely-guarded secret.

But that did not stop strong protests on the issue being directed at the Northern Ireland Secretary, Mo Mowlam, when she addressed the province's Police Federation on Tuesday.

Crucially, for those committed to building a peaceful future, the scheme has two broad conditions.

Paramilitary prisoners inside the Maze

It will only apply to prisoners from paramilitary organisations which are observing the ceasefire whose political leaders have agreed to co-operate with the independent commission on decommissioning weapons.

Those serving fixed-terms will have their sentences reduced by two-thirds; those serving life will have their terms cut by a third. Anyone still in prison at the end of two years will then be allowed out.

The prospect of convicted killers being allowed back into the community has angered many people, especially unionists and Conservative MPs.

Unprecedented step

That led to Ms Mowlam taking the unprecedented step of briefing the Shadow Cabinet Northern Ireland sub-committee about the Bill, in an effort to reassure members.

She was presented with a series of proposals for tightening up the legislation which she agreed to consider. But the prime minister's official spokesman declined to say whether any of these had been worked into the Bill.

However, Downing Street has sought to allay the fears of sceptics.

Recall clause

The BBC's political correspondent Carole Walker says the prime minister's office has stressed that each release case will be judged on its own, individual merits.

It also pressed the point that each prisoner will be out on licence and can be recalled if necessary.