'Doubts Appear' As EU, Britain Work To Finalise Last-Minute Brexit Deal

Negotiators appear close to clinching an eleventh-hour Brexit deal, although British MPs in the House of Commons still have to approve any agreement.

Britain and the EU are on the verge of a last-minute Brexit deal but Prime Minister Boris Johnson still has work to do at home to ensure his government and factious parliament approve the plan.

European Council President Donald Tusk said in theory, the two sides could have an agreement as soon as Thursday.

"The basic foundations of this agreement are ready and theoretically we could accept a deal tomorrow," said Tusk, who will chair a summit of EU leaders, including Johnson, on Thursday and Friday.

However, Tusk said in comments broadcast by Polish broadcaster TVN 24 that "certain doubts have appeared from the British side", a reference to Johnson's need to win over politicians who fear he may have conceded too much.

French President Emmanuel Macron said an agreement was being finalised and hoped it could be approved on Thursday.

"I want to believe an agreement is being finalised and that we will be able to endorse it tomorrow," Macron said at a news conference with German Chancellor Angela Merkel in Toulouse on Wednesday.

Merkel said she believed slightly more that a deal was possible.

Images: Getty

The EU leaders could sign off a deal at their summit but any approval would be conditional on the British House of Commons backing it at a special sitting on Saturday.

A short delay of Britain's October 31 departure date would follow to polish the detail.

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If Johnson fails to nail down the terms of Britain's exit from the EU, or fails to get a deal ratified in the UK house, he will almost certainly have to seek a longer extension of the departure date more than three years after the country voted in a referendum to leave.

After another day of technical talks in Brussels, EU officials said an agreement had been reached on customs arrangements for Northern Ireland.

"Theoretically, we could accept a deal tomorrow," Donald Tusk said. Image: AAP

They also said consensus had been reached on "level playing field" provisions on labour and environment standards that the EU has insisted on to ensure fair competition under a new trade deal after Brexit.

But overall backing from the British government was still needed to seal an agreement, an EU diplomat said.

Pro-Brexit lawmakers from Johnson's governing Conservative Party say they will only back a deal if it has gained the support of the Democratic Unionist Party (DUP) which fears Northern Ireland could be left behind in the EU's orbit when Britain leaves.

Johnson's spokesman said towards the end of Wednesday that talks with the DUP were still underway in London.

Irish Prime Minister Leo Varadkar said earlier on Wednesday that if an agreement cannot be reached before the summit, there was still time left to act before the October 31 deadline.

"October 31 is still a few weeks away and there is the possibility of an additional summit before that if we need one ... Although time is running short, I am confident that (Ireland's) objectives can be met," he said.