THE EU has closed ranks behind Ireland as Jean-Claude Juncker warned that the Commons vote to try to scrap the Irish backstop had increased the risk of Britain’s “disorderly exit” from the EU.

The European Commission President’s remarks came as Theresa May was holding her first Brexit meeting with Jeremy Corbyn at Westminster to see if there was any common ground between them on the way forward on Brexit. None appeared to have emerged.

Addressing the European Parliament, Mr Juncker made clear the EU27 was four-square behind Dublin, telling MEPs: “Ireland's border is Europe's border and it is our Union's priority."

He stressed how the idea of "alternative arrangements" to the backstop contained in the Brady amendment passed by MPs on Tuesday, had already been discussed in negotiations and was mentioned in the Political Declaration on future relations.

But he noted: "A concept is not a plan. It is not an operational solution."

In London, No 10 explained “alternative arrangements” could include technological solutions, a unilateral exit clause and a time-limit as well as trusted trader schemes.

Also addressing MEPs, Michel Barnier, the EU’s chief negotiator, made clear the Withdrawal Agreement, containing the backstop plan, would “not be renegotiated”. He said the process was “tough,” adding: “I find it hard to accept this blame-game they are trying to play against us."

Emmanuel Macron, the French President, was adamant that the Withdrawal Agreement was "not renegotiable" while a spokesman for German Chancellor Angela Merkel said reopening the deal was "not on the agenda". Her colleague Heiko Maas, the German Foreign Minister, added: "Germany and the entire Union are firmly on Ireland's side. We will not allow Ireland to be isolated on this issue."

Simon Coveney, Ireland’s deputy premier, stressed how his Government had seen no alternative arrangements that met the essential threshold of avoiding a hard border. “We need a backstop or insurance mechanism based on legal certainty and not just wishful thinking," he declared.

Yesterday afternoon, his colleague Leo Varadkar spoke with the Prime Minister by phone. Dublin issued a statement stressing how Ireland’s and the EU’s position on the backstop was “unchanged” and that the latest developments had “reinforced the need for a backstop, which is legally robust and workable in practice”.

At Westminster, the Labour leader emerged from his talks with Mrs May, saying they had been "serious" and “exploratory”.

He explained how he had "set out the Labour case for a comprehensive customs union with the European Union in order to protect jobs in this country".

Mr Corbyn warned: "The whole process looks like it's running down the clock by saying, well, it's either the problems and the difficulties of no-deal or support a deal that's already been rejected by the House of Commons. I'm suspicious there is a programme of running down the clock here."

Suggestions from Labour sources that the PM had signalled a climbdown on a customs union with the EU were smartly rejected by No 10, which made clear all Mrs May had done was no more than “ask questions” about Labour’s policy for a UK-EU customs union.

Earlier during a rowdy PMQs, Mrs May accused the Labour leader of "risking no-deal," pointing out how he had "opposed every move" by the Government to get a deal with Brussels.

Mr Corbyn said the PM might have temporarily united her "very divided party" but stressed how she had to “move on from the red lines she put down in the first place," reiterating his belief that a customs union and "strongest possible deal" with the single market would break the Brexit impasse.

In a bitter clash, the SNP’s Ian Blackford accused Mrs May of acting with “sheer irresponsibility” in regards to the backstop.

On Tuesday the Highland MP came under heavy Conservative fire for accusing the PM of “ripping up the Good Friday Agreement,” a charge she claimed was “frankly irresponsible”.

Over the coming days, the PM is expected to have more talks with Tory colleagues to help form her strategy for when she returns to Brussels, expected next week, to try to reopen the Withdrawal Agreement to scrap the backstop.

Mr Blackford suggested she did "not have a cat in hell's chance" of doing so.

In other developments:

*The DUP's Nigel Dodds claimed Mr Barnier had "blown a hole" in the notion of the backstop, pointing out how the EU chief negotiator had said some checks and controls could be done away from border, suggesting this meant backstop would not be necessary;

*Ardent Brexiteer Jacob Rees-Mogg said he remained prepared to see the UK leave without a deal if the EU refused to reopen negotiations, suggesting this would mean Brussels forgoing the £39 billion divorce settlement;

*Barclays bank is to move almost £170 billion of assets from the UK to Ireland as the bank prepares for a possible no-deal outcome;

*Michael Russell, the Scottish Government’s Constitutional Relations Secretary, attended the Cabinet Committee on Brexit preparedness;

*Dominic Grieve, the Conservatives’ former Attorney General, admitted it was possible the Tory Party could "fall apart" over Europe;

*Nigel Farage, the former Ukip leader, said the prospect of a no-deal Brexit had increased because of the attitude of Brussels "fanatics" who refused to compromise;

*Mr Corbyn's spokesman declined to reveal what, if any, sanctions would be taken against Labour MPs, who defied the party whip and did not vote for the Cooper amendment on extending Article 50 and

*the DUP's Brexit spokesman Sammy Wilson said it was "perfectly possible" for Mrs May to negotiate a revised deal without the backstop.