A Brexit deal has been reached by negotiators in Brussels and will be the focus of a crunch Cabinet meeting on Wednesday.
A UK Government source confirmed that agreement had been reached at a "technical level" but Theresa May will need to win the support of her Cabinet.
There has been no official confirmation from either Downing Street or Brussels.
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Irish broadcaster RTE reported that a "stable" text had been agreed on the thorny issue of the Northern Irish border.
The broadcaster said the deal involved one overall backstop in the form of a UK-wide customs arrangement, but with deeper provisions for Northern Ireland on customs and regulations.
The developments came after the Prime Minister told Cabinet on Tuesday morning that a "small number" of issues remained to be resolved and her de facto deputy David Lidington described a deal as "almost within touching distance".
Labour leader Jeremy Corbyn has reiterated that the party will look at the deal, but added that it was "unlikely" to be a good deal.
"We will look at the details of what has been agreed when they are available," he said.
"But from what we know of the shambolic handling of these negotiations, this is unlikely to be a good deal for the country.
"Labour has been clear from the beginning that we need a deal to support jobs and the economy - and that guarantees standards and protections.
"If this deal doesn’t meet our six tests and work for the whole country, then we will vote against it."