Nicola Sturgeon could announce a second independence referendum this week if Theresa May does not give Scotland a special Brexit deal.
The Scottish first minister is holding a press conference on Monday (13 March) where she is expected to deliver an ultimatum to the prime minister ahead of a Commons vote on whether MPs get a "meaningful" say on the final Brexit deal.
Following royal assent, May could be able to trigger Article 50 by Tuesday when she would inform Brussels of the UK's decision to leave.
The Telegraph reports that Sturgeon will call the referendum if the prime minister does not include demands that the EU gives Scotland special treatment.
This could encourage MPs keen to avoid the rupture of the UK to back the Article 50 amendment by the Lords, which requires parliament to vote on the final exit deal.
Sturgeon wants Scotland to stay in the single market and has said that autumn 2018 would be the right time for another ballot. Tory sources said the prime minister would not be likely to allow a referendum until after Brexit in March 2019.
Foreign Secretary Boris Johnson said on Sunday that it would not be a problem if Britain leaves the EU without a deal.
But a cross-party campaign warned that no trade deal with the European Union would put Britain in the worst position of any of the other industrialised economies. Research by the House of Commons library, commissioned by Labour MP Pat McFadden, found that all G20 countries had some sort of trade deal with the EU.
"The government is flirting, as a negotiating tactic, with an option that poses huge dangers to UK industry, services and agriculture," McFadden said, according to The Guardian.
The vote to trigger Article 50 is likely to pass in the Commons on Monday as rebel Tory MPs admit they are unlikely to get the numbers they need to block May, in part due to the support she will get from some Labour and DUP MPs, the Financial Times reported.
International trade secretary Liam Fox told Sky News that if if there were no deal, "Of course it would be bad. But it would not just be bad for the UK, it's bad for Europe as a whole".
Meanwhile, the heads of 35 Oxford colleges have signed a letter asking MPs to let EU citizens stay in the UK after Brexit to prevent academics leaving the country.
In a letter to The Times they say that there is not enough clarity over whether EU citizens currently resident in Britain could stay post-Brexit.
"Our EU colleagues are not reassured by a government which tells them that deportation is not going to happen but declines to convert that assurance into law; some are worried, some are desperate, some are already making plans to leave," the letter said.