After the two hour session between the Ulster Unionists and the nationalist Social Democratic and Labour Party, the SDLP described the meeting as "honest and straight".

The encounter was part of former US Senator George Mitchell's review of progress in implementing the Good Friday Agreement.

The meeting focused on finding a resolution of the deadlock over decommissioning and devolution which have blocked political progress in the province.

Relations between the two parties have been strained after a summer of recrimination over the failure to establish a power-sharing executive and the decision of SDLP deputy leader Seamus Mallon to quit as deputy first minister.

After Wednesday morning's meeting Mr Mallon said the parties had got down to the heart of the problem.

"We will continue to give it every effort we have to ensure, if it can be got, that we do get to a resolution of this problem," he said.

SDLP team: Talks "got to heart of problem"

"In the approach of the parties we have met so far with Senator Mitchell we detect the same desire to see if we can solve the problems."

A meeting between Sinn Fein and Senator Mitchell is scheduled for Wednesday afternoon.

But ahead of that session Sinn Fein President Gerry Adams was downbeat about the chances for success of the review.

"There is a need for people to work together as opposed to working against each other," he said.

"There needs to be a political will - that seems to be absent at the moment."

'Prepared to listen'

Earlier, as he arrived at the Stormont talks venue, Ulster Unionist leader David Trimble said he was prepared to listen to what the SDLP had to say but he had been disappointed by recent attacks on unionists by leading SDLP members.

He said he had stated his position "clearly and unambiguously to Sinn Fein" last night but the question remained whether they were truly committed to peace.

"The crucial question we will ask with regard to any proposals is: will they work, will they deliver?"

BBC NI's Mark Simpson reports on the Stormont Review talks

George Mitchell's review was sparked by the collapse of talks at Stormont in July, following the Ulster Unionists' refusal to sit in government with Sinn Fein until the IRA begins to decommission its weapons.

On Tuesday, David Trimble and Sinn Fein president Gerry Adams met for two hours at Stormont, Belfast, but there was no indication that any real progress had been made.

Mr Adams then spent an hour with a delegation from the SDLP.

George Mitchell sat in on both meetings. Afterwards, Mr Adams was asked if he believed a deal with David Trimble was possible.

'Best bet'

Mr Adams said: "I think we all have to accept, the unionists have to accept, that the Sinn Fein leadership is the best bet they have.

"We have to accept that this current UUP leadership and the other leaderships in this process are the best bet that we have."

Mr Trimble made no comment on the Sinn Fein meeting when he left Stormont.

Although there was no breakthrough at the meeting, it did re-establish a working relationship between Gerry Adams and David Trimble.

Further meetings are expected between Sinn Fein and the Ulster Unionists but no firm time has been set.