European Union can not be 'held hostage' to Brexit crisis: French President Macron

Mr Varadkar, who met French President Emmanuel Macron in Paris on Tuesday, said he was "heartened" by the continuing "enormous French support" for Ireland during the Brexit negotiations.

Ms Merkel was quoted as saying she will fight until the very end for an orderly Brexit and use her Irish trip to consider the Border situation and solutions that could prevent a hard Brexit.

In the event of a "no deal" Brexit, the Irish border would become the only land frontier between non-EU Britain and the rest of the bloc and would therefore in theory need to have customs controls. The bulk of Irish exports to the continental European Union are shipped via the UK.

Dr Merkel is expected to express strong solidarity with the Irish government, but - no doubt - she will also question the Taoiseach about how Ireland hopes to achieve its twin objectives, in a no deal scenario, of protecting the EU's Single Market while also ensuring there's no return to the borders of the past.

He called on them to come up with options "now" - warning that a potential long extension to the Brexit process should not be taken for granted.

Simon Coveney said Ireland had intensified its no-deal contingency planning with the EU Commission but checks at EU ports on Irish products were not a runner.

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"That is a complex challenge and we always said it would be".

"And we certainly wouldn't want it getting through the Republic of Ireland into the European Union", he said.

Prime Minister Theresa May held talks with Labour party leader Jeremy Corbyn on Wednesday in the hope of agreeing a position which could win a majority in the House of Commons in the coming days to allow her to request a short delay to Article 50.

Meanwhile, the United Kingdom faces a potentially lengthy delay to Brexit, Philip Hammond said as he indicated the Tories could be prepared to compromise on a customs union.

Britain, Ireland and the European Union fear the installation of physical customs infrastructure on the border could reignite largely dormant sectarian tensions and prove a tempting target for militants seeking a united Ireland and those who oppose it.