Ireland says UK cannot unilaterally scrap border backstop

Neither Ireland nor the European Union would ever sign up to a backstop agreement to keep the Irish border open after Brexit that could be ended unilaterally by Britain, Ireland's foreign minister said on Monday.

The sides in the negotiations have signalled progress on agreeing customs arrangements for an emergency Irish border fix but differences persist on the lifespan of the so-called "backstop".

"The Irish position remains consistent and v clear that a 'time-limited backstop' or a backstop that could be ended by UK unilaterally would never be agreed to by Ireland or the European Union," Irish Foreign Minister Simon Coveney said.

"These ideas are not backstops at all + don't deliver on previous UK commitments," he added on Twitter.

Coveney made his comment after Britain's Daily Telegraph reported that Prime Minister Theresa May's Brexit Minister Dominic Raab had privately demanded the right to pull Britain out of the backstop after three months.

With just five months until Britain is due to exit the EU, May has yet to nail down a divorce deal, with the Irish border insurance arrangement to keep open the border between British-ruled Northern Ireland and EU member state Ireland still the oustanding issue.

Cautious optimism that a deal between the EU and London may be in the offing has also been kept in check by the reality that such an agreement might not pass the British parliament.

Coveney's message quickly won endorsement from the EU's deputy Brexit negotiator, Sabine Weyand, who reacted by saying: "Still necessary to repeat this, it seems."

The latest proposal on the backstop, according to sources in Brussels, would keep all of Britain in a customs arrangement with the EU, as London has sought. It would also keep Northern Ireland in the customs union of the EU, as long insisted by the bloc.

But London and the bloc have still not agreed how long such an insurance policy would last. Britain wants to limit it while the EU says any clear cut-off date attached to the backstop would defeat its purpose.

"We are not there yet," the European Commission's chief spokesman, Margaritis Schinas, told reporters on Monday.

After a meeting in Dublin on Friday with Britain's Cabinet Office Minister David Lidington, May's de facto deputy, both Coveney and Lidington said the two sides were "very close" to resolving differences on the border issue.

Lidington also said the British government would stand by the written commitments it had already made on the backstop, which include an agreement that it would apply unless and until a better solution is found.

The EU has suggested that the tweaked "two-tier" backstop covering all of the UK could give mainland Britain some scope to set its own trade rules while keeping Northern Ireland aligned with the EU.