Ireland will not be left alone in the event of a no-deal Brexit, the European Commission president has said.

Jean-Claude Juncker said “alternative arrangements” could “never replace the backstop”.

Mr Juncker made the comments alongside Irish premier Leo Varadkar following talks between the two leaders at the European Commission in Brussels.

Mr Varadkar dismissed the UK Government’s alternative arrangements concept as a potential solution to the current Brexit impasse.

“We need to bear in mind that this majority that did exist in the House of Commons for ‘alternative arrangements’ probably only exists because alternative arrangements can mean whatever you want them to mean,” Mr Varadkar said.

“I don’t believe that would have passed if people had to actually get into the details of what alternative arrangement might mean or might not mean.”

He said he had concerns about the idea of “alternative arrangements” and that it could not result in the “deletion” of the backstop, while Mr Juncker said the backstop was needed for “obvious, vital reasons” and it could not be abandoned.

“The backstop is a guarantee for Ireland and it is a guarantee for the European Union because the Irish border is a European border,” Mr Juncker said.

He also said the EU “could not accept the idea which has been circulated around that the Withdrawal Agreement could be reopened”.

Mr Juncker rejected giving the UK a way to unilaterally pull out of the backstop.

“A safety net is not a safety net if it can be destroyed by the unilateral actions of one of the parties,” he said.

The Taoiseach was in the Belgian capital for talks with senior EU representatives to discuss preparations for what EU Council president Donald Tusk described as the “fiasco” of a no-deal Brexit on March 29.

Mr Varadkar said he was confident that a solution could be found to the current situation.

He also said the Irish government was not making preparations for any border infrastructure, but added that it was important to remember that the border was not just a border between Northern Ireland and Ireland, it was also going to be the new EU and UK frontier.

Their comments came after a press conference earlier in the day where Mr Tusk said he had been wondering “what that special place in hell looks like, for those who promoted Brexit, without even a sketch of a plan how to carry it out safely”.

Mr Tusk added that the EU was not making “any new offer” to the UK Government on the Brexit deal and he repeated the EU’s insistence that the Withdrawal Agreement reached with Theresa May last year could not be reopened.

Speaking alongside Mr Tusk, Mr Varadkar said the EU was open to further discussion with the UK Government on Brexit but the Withdrawal Agreement remained “the best deal possible”.

In relation to the backstop, he added: “While we expect that the backstop will never be used, we agreed again today that it is needed as a legal guarantee to ensure that there is no return to a hard border on the island of Ireland while protecting the integrity of our European single market and customs union.

“I think the events in London and the instability in British politics in recent weeks demonstrates exactly why we need a legal guarantee and a solution that is operable, that we know will work and will last.”

During his visit, Mr Varadkar also met with the chairman of the European Parliament steering group on Brexit Guy Verhofstadt, EU chief Brexit negotiator Michel Barnier, and EU Commissioner Phil Hogan.

The leaders discussed the detailed contingency planning under way in the event of the UK crashing out of the EU without a deal.

The British PM is due to hold meetings with Mr Tusk, Mr Juncker and Mr Barnier in Brussels on Thursday before visiting Dublin late on Friday to discuss Brexit with her Irish counterpart.

It will be the first time Mrs May meets EU leaders and Mr Varadkar since the Withdrawal Agreement was overwhelmingly rejected in the House of Commons last month.

Prime Minister Theresa May at Stormont
Prime Minister Theresa May arrives at Stormont (Brian Lawless/PA)

During a two-day visit to Northern Ireland on Tuesday, Mrs May restated her “unshakeable” commitment to avoiding a hard border in Ireland after Brexit.

The final day of her trip culminated with meetings on Wednesday with all five of the main parties at Stormont House.

A spokesman for Mr Varadkar said Mrs May was coming to Dublin to discuss the ongoing efforts to restore the Northern Ireland executive and protect the Good Friday Agreement in light of the current Brexit situation.