Chris Heaton-Harris said he would give more information next week and would be meeting the parties in the meantime.

Devolved government in NI has not functioned since an election in May.

The Democratic Unionist Party (DUP) blocked the restoration of power-sharing in its protest against the post-Brexit trading arrangements called the Northern Ireland Protocol.

Legislation says that an election must be held within 12 weeks and it had been expected that a poll would take place on 15 December.

The Northern Ireland parties had expected the secretary of state to signal a date for the election on Friday.

However, Mr Heaton-Harris denied he had made a U-turn, saying an election did not have to be called immediately.

"I hear it when the parties say that they really do not want an election at all," he said.

"But nearly all of them are parties who signed up to the rules, the law. That means I need to call an election so you'll hear more from me on that particular point next week."

He added: "I will be calling an election".

Mr Heaton-Harris said he had met with Virginia McVea, Northern Ireland's chief electoral officer, and discussed issues around operational concerns she wants to "make sure are addressed as we move forward".

He said joint authority in Northern Ireland was "something we simply will not consider".

Speaking in Dublin at around the same time as Mr Heaton-Harris was speaking in Belfast, Taoiseach (Irish prime minister) Micheál Martin said: "In my view we should take the opportunity to pause and see if we can get the institutions back and, parallel with that, have substantive negotiations between the UK government and the European Union.

"The law does provide for an election, I acknowledge that, but we know what elections can do, they can lead to further polarisation."

'Bizarre U-turn'

Sinn Féin Deputy Leader Michelle O'Neill said the move was a "bizarre U-turn" from the NI secretary.

"We wouldn't be in this position if the DUP had honoured the result of the May election," she said.

"We need an assembly and executive up and running to serve people through tough times.

Michelle O'Neill says the move is a "bizarre U-turn"

"I have reached out to the secretary of state and asked to speak to him.

"It's not acceptable that six months after the public gave us a mandate to work together, six months and the DUP is still blocking the outcome of that election because they didn't like the result," she added.

SDLP leader Colum Eastwood said Mr Heaton-Harris must drop the idea of an assembly election and focus on restoring the Stormont institutions.

"The secretary of state's failure to outline details of an assembly election today should be the end of the idea," he said.

DUP Leader Sir Jeffrey Donaldson said "chaos" continued because of uncertainty around another election.

"The Northern Ireland Office have been talking up the prospect of an election for some time but evidently no decision has been taken and we're ready to fight an election," he said.

DUP leader Sir Jeffrey Donaldson said "chaos" continued due to uncertainty over an election

He said his message to the the secretary of state was that resolving issues around the protocol was a priority.

He called for "decisive action to restore Northern Ireland's place in the UK internal market and remove the debris of the protocol".

He said that until then "we are not in a position and there is no consensus for the restoration of the devolved institutions".

Alliance MP Stephen Farry said there had been no "pressure" applied to the DUP by Westminster to get the party to go into government.

"We are in political vacuum but I don't think an election is going to address that vacuum so we will still be in that dilemma on the far-side of an election," he told BBC's Evening Extra programme.

However, he added that there should be a "cautious welcome if there is some degree of reflection happening inside the NIO".

Ulster Unionist Party leader Doug Beattie said not enough had been done to get Stormont up and running.

"Not at one stage have all the party leaders been brought together to sit together," he said.

"I would urge the secretary of state to strive to do more because an election will not help," he added.

He said negotiations with the EU over the protocol could still go ahead if Stormont was restored.

Independent Unionist MLA Claire Sugden told the programme that having no ministers in place meant "important decisions enabling departments to run on a daily basis cannot be taken".

People Before Profit MLA Gerry Carroll said it was a "farcical move". However, he said that he welcomed an election as an opportunity for people to "cast their verdict on the DUP's obstructionism".

Traditional Unionist Voice leader Jim Allister said Mr Heaton-Harris should "stabilise Northern Ireland" by focussing on the resolving the issues raised by the protocol.