The Northern Ireland talks have broken down with Taoiseach Enda Kenny and British prime minister David Cameron returning home early after failing to win an agreement.

Kenny and Cameron left Stormont after local parties stated the British prime minister’s offer of £1 billion ($1.6 billion) to the Northern Executive over the coming five to six years was inadequate.

Sinn Féin Deputy First Minister Martin McGuinness stated: “There is a common view among the Northern Executive that none of us believe that this is a credible financial package.”

The departure of the two leaders caught everyone by surprise as they were due to stay until this evening at the earliest.

The parties in the North are deadlocked over flags, symbols, marches, the legacy of the past and budgetary issues. Advisors to the British and Irish leaders say their departure was intended to give a “reality check” to the parties.

Sinn Féin president Gerry Adams was deeply critical of the two leaders, tweeting that this was the “most amateurish, ham-fisted episode” he had ever been involved in and praising the remaining parties for keeping the talks going.

Enda & David may have left but Sinn Féin & other parties keep going.

— Gerry Adams (@GerryAdamsSF) December 12, 2014

“A deal hasn’t been possible,” said Cameron. “What I hope will happen now is the politicians here in Northern Ireland will work together to agree these vital issues about parades, about flags, about the past, about their budget. If they come to agreement then that sort of financial power can come to bear. But if there isn’t agreement that financial firepower isn’t there,” he said.

“But I think things are better today than they were yesterday,” said Cameron.

Kenny said the work would continue to work with the parties to try to end the impasse.

“Politically there is not agreement on the issues that were tabled (put forward) last evening. That does not mean that the politicians who were elected and who have responsibility devolved to them cannot conclude on a number of these matters,” said Kenny.

“From my point of view and I am sure from the prime minister’s point of view we will be available to come back whenever a deal is concluded by the political process here and move the opportunity for the people of Northern Ireland to have a better place in the future. It was not possible to conclude it today but good work has been done,” added Kenny.