STORMONT’S Deputy First Minister Martin McGuinness has resigned, signalling the end of an historic power-sharing administration in Northern Ireland.

The Sinn Fein veteran, who had held the position for 10 years, said there would be “no return to the status quo” as he left, bringing to an the end a pact between the Democratic Unionist Party (DUP) and Sinn Fein which had symbolised an era of peace and reconciliation.

His resignation will force First Minister Arlene Foster from office and means the collapse of the fragile government established when the late Rev Ian Paisley agreed to put aside differences with Sinn Fein over the constitution and share power with them in May 2007.

Sinn Fein has seven days to re-nominate a new deputy first minister following McGuinness’ resignation. However, the party is adamant it will not replace him.

It is likely that next Monday the Conservative Northern Ireland Secretary James Brokenshire will be put in charge with the onus on him to call a new election to the Assembly.

McGuinness announced he was stepping down after Foster repeatedly refused to stand aside to allow a probe into a botched green energy initiative – a scheme that has left Stormont facing a £490 million overspend and which she set up as economy minister.

McGuinness said he was resigning with “deep regret and reluctance”.

“We in Sinn Fein will not tolerate the arrogance of Arlene Foster and the DUP,” he said. “I believe today is the right time to call a halt to the DUP’s arrogance.”

McGuinness is experiencing health problems but he insisted that had not influenced his decision.

He said: “The First Minister has refused to stand aside, without prejudice, pending a preliminary report from an investigation. That position is not credible or tenable. We now need an election to allow the people to make their own judgment on these issues democratically, at the ballot box.”

Foster presided over the ill-fated Renewable Heat Initiative while economy minister, but refused to accede to Sinn Fein’s demand for her to step aside to facilitate an inquiry into her actions.

The state-funded RHI was supposed to offer a proportion of the cost businesses had to pay to run eco-friendly boilers, but the subsidy tariffs were set too high and, without a cap, it ended up paying out significantly more than the price of fuel.

Claims of widespread abuse include a farmer allegedly set to pocket around £1 million in the next two decades for heating an empty shed.

McGuinness’s move came hours after Foster accused him of playing a political game of chicken and warned she would not blink first.

“If he is playing a game of chicken, if Sinn Fein are playing a game of chicken and they think we are going to blink in relation to me stepping aside they are wrong – I won’t be stepping aside,” she said.

“And, if there is an election, there is an election.”

While Sinn Fein had been due to formally call for Foster to step down in an Assembly debate next week, there had been speculation the party would pull the plug earlier.

The structure of Stormont’s Executive means a first minister cannot hold the position without a co-equal deputy first minister. McGuinness’s resignation means Foster will no longer be first minister. He said a decision on whether he would stand in the next election was an issue for “a later date”. McGuinness cited other disputes with the DUP, including Brexit, in his resignation letter. Sinn Fein, like the SDLP and Alliance Party, campaigned for Remain, while Foster’s supported Leave.

Northern Ireland voted narrowly to remain in the bloc.

Peter McLouglin, a lecturer in politics at Queen’s University, Belfast, said the development was the worst crisis facing the Stormont Assembly in recent years.

“The significance of this is massive. The previous First Minister Peter Robinson stood down for a period but nominated Foster to replace him temporarily.”

He added the crisis had happened at a bad time with the Brexit negotiations looming. “Brexit has not been getting the attention it deserves, which is very concerning,” he said.

Theresa May’s official spokeswoman said: “The Prime Minister has been kept updated on the resignation of Martin McGuinness.

“The Northern Ireland Secretary James Brokenshire is in contact with people there, encouraging all parties to continue the dialogue.”

Ireland’s Foreign Minister Charlie Flanagan spoke by phone to McGuinness and Brokenshire.

He said: “If, as appears likely, new elections to the Assembly will now be required, it behoves all parties to act responsibly in word and deed so that the political institutions of the agreement will not be damaged in the longer term.”