British Prime Minister Theresa May will seek her cabinet's approval Wednesday for a long-awaited divorce deal with the EU but hardline Brexiteer MPs warned they will seek to block it in parliament.

After months of talks, May's office announced late Tuesday that negotiators had finally struck a draft agreement on the terms of Britain's withdrawal from the European Union next March.

The pound surged following the news, which came just as Brussels stepped up preparations for a potentially catastrophic "no deal" exit.

But the deal had barely been announced when prominent eurosceptics took to the airwaves to denounce it, with speculation that high-profile resignations could follow.

Diplomats and officials warned the technical agreement, which runs to hundreds of pages, will still need to gain political approval.

Ambassadors from the other 27 EU member states will meet later in Brussels, Ireland's Prime Minister Leo Varadkar will hold a cabinet meeting and May's ministers convene at 1400 GMT.

In the hours before the cabinet meeting, May received her ministers one-by-one in Downing Street in what commentators said was a strategy to avoid a concerted revolt.

- Irish backstop -

If the British cabinet approves the text, London is hoping for a special summit of EU leaders later this month to seal the deal.

Brexit talks were stuck for months on how to avoid customs checks at the Irish border / © AFP/File

But May has faced constant criticism from Conservative MPs over her approach.

Former foreign secretary Boris Johnson, who quit the cabinet over Brexit in July, said the deal would leave Britain a "vassal state" and urged his former colleagues to "chuck it out".

Most ominously for May, the Northern Irish party which props up her government threatened to break their alliance over reports of a special arrangement for the British province.

According to media reports, the final deal includes a so-called "backstop" arrangement in which the whole United Kingdom will remain in a customs arrangement with the EU.

Northern Ireland would also effectively stay in the European single market under the proposals, meaning some checks may be required between Northern Ireland and the rest of the country, the reports said.

Arlene Foster, leader of the Democratic Unionist Party (DUP), was heading to London on Wednesday, telling Sky News that these were "worrying times."

"We cannot be separated from the rest of the UK, either in terms of customs or indeed in terms of regulatory alignment either," she said.

"Hopefully we'll actually get to see the text so that we can make our own judgment on that."

- 'Short notice' -

British and EU negotiators had stepped up their talks ahead of a deadline on Wednesday to get a deal in time to call the special summit for later this month.

European sources in Brussels told AFP that if May wins the backing of her cabinet then Wednesday's simultaneous meeting of ambassadors could be followed by a second get-together on Friday and a pre-summit meeting of EU ministers on Monday.

EU leaders could then gather at an extraordinary summit, likely on November 25, to sign off on the deal.

But several diplomats expressed caution, with one telling AFP that Monday "seems very short notice".

Failure would delay the final settlement until a formal Brussels summit in mid-December, leaving little time for May to get the deal and associated legislation through parliament.

The talks were stuck for months on how to avoid border checks between British Northern Ireland and EU member Ireland, if and until London strikes a new trade deal with Brussels.

The deal reportedly allows for a review mechanism that Britain could use to try to leave the backstop arrangement -- a key demand of Conservative eurosceptics.

Former Tory party leader William Hague warned Brexiteers that they could sabotage the whole process if they failed to back May's plan.

"If they vote down a deal because they are not happy with the details, the consequences may be that Brexit never happens," he said on the radio.

Popular tabloid The Daily Mail carried the front-page headline "Judgment Day", urging its centre-right readership to give the deal "a fair chance".

Labour leader Jeremy Corbyn said he would wait for details, but suggested the agreement was "unlikely to be a good deal for the country".

The agreement provides for a 21-month transition after Brexit during which London would follow EU rules while both sides negotiate a new trade relationship.

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