The new Northern Ireland secretary of state has emerged from his first talks with political parties in Northern Ireland and stressed his commitment to the Good Friday Agreement.

Peter Mandelson said: "What all of us need to do, all of us need to be committed to doing, is making sure that the Good Friday Agreement gets implemented."

"There is no alternative to it. There is no plan B. It is that or nothing.

"And for all our futures, creating a future for Northern Ireland in which everyone has a stake, we as political leaders have got to show leadership.

"We have got to do everything that we humanly can do to build that trust to ensure that the agreement moves ahead and is properly and fully implemented in all its respects," he said.

The new Northern Ireland secretary held separate talks earlier on Tuesday with the Unionist Unionist leader David Trimble and Sinn Fein's chief negotiator Martin McGuinness.

Mr Trimble, accompanied by a party delegation, was the first through the door at Stormont on Tuesday.

He discussed a range of issues with Mr Mandelson including the Mitchell review of the Good Friday Agreement and the Patten report on the future of policing.

Mr Trimble said: "It was a first meeting, it was a good meeting, as I am sure other parties will find that their first meetings are good too."

Later, Sinn Fein's chief negotiator Martin McGuinness emerged from his discussions with the secretary of state and said they had been "good" and "interesting".

"At the meeting we of course stressed the absolute need, the vital need, to see the implementation of the Good Friday Agreement.

"And we expressed our opinion that the British Prime Minister and Peter Mandelson were absolutely vital and key to the implementation of that agreement," he said.

In talks with Mr Mandelson on Tuesday afternoon SDLP Deputy Leader Seamus Mallon told Mr Mandelson that the only way Northern Ireland's problems could be solved was through implementing the Agreement.

Mr Mandelson also had his first meeting with the anti-Agreement DUP.

Afterwards DUP leader Ian Paisley said he did not expect Mr Mandelson to stay in his post for long and that any attempt by the new Northern Ireland secretary to push forward with the implementation of the Agreement would fail.

Mr Mandelson also carried out his first public engagement on Tuesday afternoon when he visited the Family Trauma Centre in Belfast. He then went on a walkabout around Belfast City centre.

Chairman of the current review of the peace process former US Senator George Mitchell is due to start a new round of discussions with the parties in London on Tuesday night.

The 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 began to decommission its weapons.

Sinn Fein say that it is a pre-condition that is not in the Good Friday Agreement.