Sinn Fein threatened not to support Peter Robinson as the new First Minister and instead went to the Prime Minister to discuss delays on devolution of policing and justice and the implementation of the Irish Language Act.

MLA Danny Kennedy said: "Simply to claim that no damage was done to Northern Ireland's image and reputation for political stability will not undo the damage Sinn Fein inflicted on all of us last week through their political high-wire act threatening the collapse of the Assembly and an election, just one year after the last poll.

"Business is understandably touchy about this political stability issue. Political stability came out as a major theme in everything the US business leaders said to us during the investment conference.

"Business will judge Sinn Fein not on their words but on their actions," he said.

Sinn Fein denied it had damaged international confidence by threatening to scupper Mr Robinson's nomination as First Minister.

Deputy First Minister Martin McGuinness said: "I have no doubts whatsoever that our excellent relationship with the US political administration in terms of support for our process and the US business community is going to continue.

"I'm very optimistic that the upcoming visit of the President of the United States will see us move forward even more decisively."

MP William McCrea last night claimed Sinn Fein's "attempts at brinkmanship" had failed.

"They cynically and selfishly sought to destabilise the political institutions in order to push their plans in relation to the devolution of policing and justice and the Irish language," he said.

He insisted the DUP would stick to its position of only allowing the devolution of Policing and Justice powers when there was sufficient public confidence.

"The DUP opposes any new Irish language legislation, indeed it was a DUP minister who binned this key Republican demand at Stormont. We have not moved one inch from that position.

"The truth of the matter is that Gerry Adams was desperately seeking to re-establish some credibility following the string of defeats that have been inflicted on Sinn Fein in the Assembly by unionists.

"The DUP is pleased to have binned an Irish Language Act: we have negotiated a veto on devolution of Policing and Justice and we will use it on behalf our community until they are confident enough to allow devolution of these powers to take place. The last seven days have changed nothing."