UPDATE 1-Stand together, Britain's May calls for unity on Brexit

With less than six months before Britain leaves the EU, Brexit talks have reached a stalemate over the so-called Irish backstop, a fallback plan to ensure there is no return to a hard border between Northern Ireland and EU-member Ireland.

Britain's Prime Minister Theresa May told her ministers on Tuesday they would secure a Brexit deal if they stood together, calling for a show of unity to silence those pressing her to rethink her strategy for leaving the European Union.

A day before heading to Brussels for a summit, May is keen to show she has the support of her cabinet after facing pressure from some members of her Conservative Party and the EU to change course on Brexit, Britain's biggest policy shift in more than 40 years.

With less than six months before Britain leaves the EU, Brexit talks have reached a stalemate over the so-called Irish backstop, a fallback plan to ensure there is no return to a hard border between Northern Ireland and EU-member Ireland.

The impasse has increased the possibility of Britain leaving the bloc without an agreement, a 'no deal' Brexit that could potentially disrupt trade, delay movement of goods and starve the world’s fifth largest economy of investment.

May's spokesman said the cabinet had held "a very detailed and thorough discussion" on the border issue, with the team united in rejecting any deal that would split the United Kingdom and might "trap" Britain in the backstop indefinitely.

"The PM said there will no doubt be challenging moments ahead, that is in the nature of negotiations. She said she is committed to securing a Brexit that delivers on the referendum result, safeguards jobs and security, and which preserves our union," her spokesman told reporters.

Quoting May directly, he said she told her ministers: "I am convinced that if we as a government stand together and stand firm was can achieve this."

He said ministers had shared their concerns over the backstop, playing down a "pizza summit" attended by eight of them late on Monday to discuss Brexit and whether to back the prime minister's strategy. The meeting had prompted some reports of possible resignations.

Asked whether any minister indicated they might be considering resigning, he replied: "They did not."

TENSIONS

Both sides say much of the withdrawal agreement, which sets the divorce terms for Britain's departure, has been agreed, but there are still outstanding issues, mostly on the backstop.

The EU has stuck to its position - a backstop to prevent a return to a hard border between Northern Ireland and Ireland cannot be time-limited and cannot include the whole of the United Kingdom remaining in the customs union.

Under pressure from lawmakers in her Conservative Party and from her parliamentary partners, Northern Ireland's Democratic Unionist Party, to hold firm, May must try to convince her critics that she can deliver on the backstop.

Her spokesman said ministers had discussed one possible way out of the stand-off - "a mechanism to clearly define how that backstop will end".

European Council President Donald Tusk said he would ask May at Wednesday's summit whether she had any new proposals to break the impasse. "For a breakthrough to take place beside goodwill we need new facts," he said.

The EU's chief negotiator Michel Barnier said both sides would work "calmly and seriously" in the coming weeks to try to reach agreement on the backstop.

He said the withdrawal agreement with Britain had to be "orderly for everyone and all the subjects, including Ireland".  

(With inputs from agencies.)