Paul Murphy took ill shortly before he was due to make his speech

The details were contained in a speech which Northern Ireland Secretary Paul Murphy had been due to deliver at the Labour Party conference in Brighton on Tuesday.

Mr Murphy felt unwell shortly before he was due to make his address and was taken to hospital for routine tests.

It was thought his speech might be rescheduled for Wednesday, but he will take some time off to recover instead.

Disagreements about the Stormont rules have prevented a deal to restore devolution.

However, Mr Murphy wrote in his speech that the institutions of the Good Friday Agreement "should not be beyond amendment or improvement".

He said the "prize of removing arms and paramilitarism from politics" in Northern Ireland was "within the government's grasp".

QUICK GUIDE Northern Ireland conflict

In response, Sinn Fein's Martin McGuinness signalled that his party would not tolerate any attempt to diminish the fundamentals of the Good Friday Agreement.

Mr McGuinness said the government had not shared with Sinn Fein its proposed changes.

The DUP told the BBC that they would be looking closely at Mr Murphy's speech.

The political institutions in Northern Ireland were suspended in October 2002 amid allegations of IRA intelligence gathering at the Northern Ireland Office.

Turning to the continuing pain felt by the loved ones of those killed during the Troubles, the Northern Ireland Secretary signalled an expanded role for a police team currently investigating a number of unsolved murders.

Government sources told the BBC it was believed re-examining so-called "cold cases" could bring a measure of comfort to bereaved families, even if it did not necessarily lead to prosecutions.

The sources stressed that the expanded role for the Serious Crime Review team was not being viewed as a substitute for any future commission dealing with questions about truth and the past.

The government has been under pressure from the Police Federation to provide the funding for the unit.

Analysis: Key political issues

The federation, which represents rank-and-file officers, would like the unit to examine all 1,800 unsolved murders of the Troubles, including the cases of 200 police officers.

It is thought such a large-scale "cold case" review could cost as much as �9m.

On Monday night, Ulster Unionist leader David Trimble told Labour MPs at a fringe meeting that the DUP should talk to Sinn Fein.

Ian Paisley has not taken up that invitation, but the DUP has confirmed that their leader will travel to Dublin on Thursday to meet Irish Prime Minister Bertie Ahern.

The two men have held political talks in London and at Leeds Castle, but this will be the first time the DUP leader will have led a political delegation to the Irish capital.