Downing Street has played down suggestions that a Brexit deal is imminent, after European Council president Donald Tusk appeared to indicate a breakthrough could come within the next week.

A senior UK Government source said that reports in the European media that a deal could come in the next few days should be taken “with a very large pinch of salt”.

Meanwhile, Irish foreign minister Simon Coveney cautioned against assuming that the rest of the EU would necessarily back any exit plans agreed by the UK Cabinet.

The UK Government is still working on the precise wording of a proposed review mechanism which might create a means – short of a full trade deal – to bring an end to a temporary backstop arrangement for the Irish border.

Senior ministers are poised to meet as soon as a deal is ready to be signed off, with speculation over a special Cabinet meeting as early as Saturday or Monday.

Austria’s Der Standard newspaper quoted European Commission sources at a summit in Finland as saying that EU chief negotiator Michel Barnier and Brexit Secretary Dominic Raab could meet in the next few days to seal an agreement and pave the way for a special summit of EU leaders in Brussels on November 25.

Asked about the prospects of a breakthrough in the coming week, Mr Tusk told Channel 4 News: “I hope so … but still we need maybe five, maybe six, maybe seven days.”

A Downing Street source stressed that no agreement had yet been reached and no Cabinet meeting scheduled.

“We are still in negotiations, and on that basis we don’t know when and if this will conclude,” he said.

Mr Coveney told the Irish Canada Business Association conference in Dublin: “I would urge caution that an imminent breakthrough is not necessarily to be taken for granted, not by a long shot.

“Repeatedly people seem to make the same mistake over and over again, assuming that if the British Cabinet agrees something, well, then that’s it then, everything is agreed.

“This is a negotiation and needs to be an agreement of course between the British Government, but also with the European Union and the 27 countries that are represented by Michel Barnier and his negotiating team.

“So while of course we want progress to be made and we want it to be made as quickly as possible because time is moving on, I would urge caution that people don’t get carried away on the back of rumour in the coming days.”

Theresa May last month told MPs that 95% of the deal had been agreed, although the key sticking point of the “backstop” to prevent a hard border between Ireland and Northern Ireland remained unresolved.

The Prime Minister’s plan would see the whole UK effectively agree to remain in the customs union to help avoid a hard border with Ireland as a backstop if no other arrangement can be found.

Brexiteer MPs, including Environment Secretary Michael Gove, have called on Mrs May to release full legal advice setting out how the arrangement could be ended to avoid it becoming a permanent settlement.

Former Brexit secretary David Davis said the full government legal advice on Brexit must be published and insisted how the UK could exit from the customs union must be “pinned down” before MPs and peers vote on the deal.

Leaving without an agreement would mean some “hiccups in the first year” but the UK would have “all the rights and controls over our own destiny”, he added.

Conservative Dominic Grieve has written to Cabinet Secretary Sir Mark Sedwill calling for government documents explaining any final withdrawal agreement to the public to include a full comparison with the status quo as well as with a no deal scenario.

Meanwhile, Mr Raab was subjected to a hail of ridicule after admitting he “hadn’t quite understood the full extent” to which UK trade was “reliant on the Dover-Calais crossing”.

He told a tech industry meeting in London on Wednesday: “I don’t think it is a question so much of the risk of major shortages, but I think probably the average consumer might not be aware of the full extent to which the choice of goods that we have in the stores are dependent on one or two very specific trade routes.”

Remain-backing TV scientist Brian Cox took to Twitter to ask: “How could it possibly come as a surprise to Dominic Raab that our most important trade gateway is that which is closest geographically to our most important market?”

Labour Brexit spokeswoman Jenny Chapman asked: ‪”How are we meant to trust this government to deliver a good deal for the country when we have a Brexit Secretary who doesn’t even understand the very basics of Brexit?”

Scottish National Party MSP Stewart Stevenson said: “This is a stunning admission that shows just how clueless the Tories are about their Brexit plans.

“A Tory Brexit could have a catastrophic impact on trade with the continent and leave supermarket shelves empty.”

Mr Barnier has warned of the need to fight against forces seeking to “demolish” the European project, saying: “There is now a Farage in every country.”

Speaking to the Helsinki conference of the centre-right European People’s Party (EPP), Mr Barnier warned: “The European project is fragile, it is under threat, it is perishable and at the same time it is vital.”