Britain's opposition Labour Party has ruled out a deal with Scottish leader Nicola Sturgeon that would deliver a second referendum on independence for Scotland as the price of her support for a Labour government, the Times newspaper reported.
Scottish First Minister Nicola Sturgeon has called for an extension to the Article 50 process.
May faces fierce opposition in parliament to her plan and political analysts have said she might even step down if she is decisively beaten in a vote on the issue due on December 11.
At the start of a crucial week for Theresa May, she will tell MPs leaving the European Union will enable Britain to strike "ambitious" trade deals around the world.
The first minister said "I used today's meeting with the prime minister to reiterate that it can not - and must not - be a false choice between her proposed deal and a no-deal outcome, which threatens to be utterly disastrous for jobs, business and living standards".
Further details of a looming Holyrood vote against Theresa May's Brexit deal have been revealed, with MSPs set to declare it would be "damaging for Scotland and the nations and regions of the UK".
Updating the Commons on bilateral talks at the G20 in Argentina, she will say: "For the first time in more than 40 years we will have an independent trade policy".
Meanwhile, Scottish Secretary David Mundell will give a Brexit briefing to finance companies in Edinburgh on Monday.
Those taking part in the roundtable discussion include Treasury representatives, RBS, TSB, Tesco, Lloyds Banking Group and Scottish Financial Enterprise - the representative body for Scotland's financial services industry.
"I am determined to ensure that the sector flourishes as we leave the EU".
He said the agreement on the post-Brexit relationship for financial services is that it will be of "greater depth than any other the European Union now has with a third country".
Mr Mundell added: "Businesses and the public alike want the UK Government to get on with securing a deal. That is what we are doing".