The Foreign Affairs Minister Charlie Flanagan says he will now engage with the United States on the situation in Northern Ireland.

Mr Flanagan says while the situation is fragile, they are not at the point of no return.

Power-sharing remains on the brink of collapse in the political row sparked by a murder which police are linking to the IRA.

Minister Flanagan says he is hopeful talks next week will work.

Northern Ireland's Deputy First Minister Martin McGuinness has sought to play down the crisis, saying the parties have 'four to six weeks' to overcome their problems.

Mr McGuinness says the parties need to re-discover their previous spirit of co-operation to get around the current crisis.

Sinn Féin says it is willing to attend a new round of crisis talks on Monday to overcome the recent crisis following the murder of Kevin McGuigan.

Mr McGuinness says the unionist parties in particular need to learn to speak to each other.

Meanwhile Northern Ireland's new acting First Minister Arlene Foster says alleged links with Sinn Féin to the IRA are "a cancer at the heart of government".

Ms Foster says the links between politicians and paramilitaries are a matter that "must be dealt with".

She says the new round of talks beginning on Monday must deal with the central issue of the IRA and its alleged link with Sinn Féin.

Sinn Féin vice president Mary Lou McDonald said Foster's claims are "rubbish" and "sensationalist fiction."

"I’m sorry that Arlene would rather indulge herself in the sort of sensationalist fiction.

"There is no cancer in Sinn Fein we are an open, democratic party - the IRA has gone away and the war is Over and it;s time for people to catch up," she said.

The British Prime Minister David Cameron says he is "gravely concerned" about Northern Ireland's faltering power-sharing government.

While the Sinn Féin leader Gerry Adams told Newstalk Breakfast: "Whatever can be humanly done to reassure people, to get things back on track, we will do it."

First Minister Peter Robinson stepped down yesterday and most of his Democratic Unionist Party (DUP) ministers quit over a crisis sparked by a murder linked to members of the IRA.

Arlene Foster is now the sole unionist in Northern Ireland's power-sharing government after the mass resignation of her fellow party members.

Mr Robinson walked out after the DUP failed to get the Assembly adjourned for a period to allow crisis talks over the killing of Kevin McGuigan.