Image copyright Reuters Image caption DUP MP Sammy Wilson has accused the prime minister of rolling over to the EU

Theresa May's credibility as prime minister is now being questioned, the DUP's Brexit spokesman has said.

Sammy Wilson made the comments after the EU granted a "flexible" extension to the Brexit process until 31 October.

Mr Wilson, whose party leader Arlene Foster has been in Brussels meeting EU officials, said the UK had "rolled over" to the EU.

Mrs Foster has insisted the prime minister must address the Irish border backstop in the Brexit deal.

Theresa May has acknowledged that there was "huge frustration" that she had to ask for more time.

On Thursday, Mrs Foster met the EU's chief Brexit negotiator Michel Barnier along with the party's MEP, Diane Dodds.

They were accompanied by Conservative Brexiteer MPs Iain Duncan Smith and Owen Paterson, a former Northern Ireland secretary.

Image copyright Getty Images Image caption Owen Paterson, a leading Brexiteer, accompanied the DUP to Brussels

Ahead of the visit, Mrs Foster had accused the EU of ignoring the concerns of unionists in relation to the Irish border backstop - but the EU has repeatedly said the withdrawal agreement cannot be re-negotiated.

Sinn Féin vice-president Michelle O'Neill said that by opposing the Brexit backstop, the DUP is "actively working" against the best interests of people the party claims to represent.

"The DUP also continue to ignore the constant warnings from our business community, our agricultural sector, universities, trade unionists and many others who have all advocated the Backstop as the best way of protecting our interests from the worst impacts of Brexit."

What is the Irish border backstop?

The backstop is an insurance policy - designed to avoid a hard border "under all circumstances" between Northern Ireland and the Irish Republic.

If the UK leaves the customs union and the single market that could mean goods would have to be checked as they crossed the frontier.

It would keep the UK in a "single customs territory" with the EU, and leave Northern Ireland in the EU's single market for goods.

Unionists are opposed to it as they say the differences in trade between NI and Great Britain could pose a risk to the integrity of the union.

Read more here.

Mr Wilson, the East Antrim MP, told BBC News NI that Mrs May had repeatedly broken promises - and that she had "rolled over" to the EU.

He said: "She was the prime minister who said we would be leaving on the 29th of March not once, but 108 times, and she has not honoured that promise either.

"I think she has to ask herself given the amount of promises broken to different groups of people, does she have any credibility?"

On Thursday, Conservative MP Daniel Kawczynski, who resigned from the Eurosceptic European Research Group (ERG), said the Brexit deadlock had put Theresa May at the "mercy of unrealistic demands" from the DUP and elements of the ERG.

Theresa May has insisted MPs have a duty to break the deadlock at Westminster - the Conservatives and Labour have been engaged in talks but there has not been a breakthrough yet.

Speaking in the Commons, the DUP's deputy leader Nigel Dodds said the EU had backed down by granting another extension, and called on the PM to "learn the lesson" of that, by pushing for changes to the backstop.

Image copyright EPA Image caption Theresa May has insisted that the UK can still leave the EU next month, if MPs can rally round a deal

Mrs May told MPs the government had "an accelerated timeline to determine alternative arrangements", and had also committed money to ensuring those alternative arrangements would replace the backstop.

However, she stressed that the best way to ensure the backstop did not take effect was to agree a deal and begin negotiating the UK-EU future relationship.

European elections

Meanwhile, the Northern Ireland Electoral Office has confirmed it is moving ahead with plans for the European elections on 23 May.

Theresa May said the UK must now hold the elections, or leave the EU on 1 June without a deal - if MPs have not passed the withdrawal agreement by 22 May.

The Chief Electoral Officer for NI, Virginia McVea, said nominations for the elections will open on 16 April.

Counting would take place on Monday 27 May.

The DUP has already said its current MEP Diane Dodds, had been ratified as the party's candidate.

Sinn Féin is due to hold a nomination convention next week. Martina Anderson has represented the party in Brussels since 2012.

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It is not clear if the Ulster Unionist Party's current MEP, Jim Nicholson, will stand again or if someone else will run for the party.

Former head of the EU Commission office in Belfast, Jane Morrice, told BBC's The View she would stand as an independent candidate as she feels she has a "duty" to run.

If the UK takes part in the elections, it means extra seats that would have been allocated to the Republic of Ireland will remain Northern Ireland seats.

That could have an impact on former SDLP leader Mark Durkan's chances of taking a seat for Fine Gael in Dublin.

The party had decided to stand two candidates, Mr Durkan, and Frances Fitzgerald, in the new four-seat constituency - but the UK's participation in the European elections would reduce the number of seats available back to three.