MPs will be called to Parliament for a special Saturday sitting in a decisive day for the future of Brexit.
Parliament will meet on 19 October after a crunch EU summit, seen as the last chance for the UK and EU to agree a deal ahead of 31 October deadline.
If a deal is agreed, Boris Johnson will ask MPs to approve it, but if not, a range of options could be presented.
These could include leaving without a deal, and halting Brexit altogether.
The additional day in the Commons will coincide with a anti-Brexit march run by the People’s Vote campaign, which could see thousands of protesters heading to Westminster.
The prime minister has said he is determined that the UK will leave the EU on 31 October, despite legislation, known as the Benn Act, which requires him to write to the EU requesting a further delay if a deal is not signed off by Parliament by 19 October, or unless MPs agree to a no-deal Brexit.
The House of Commons has only sat on four Saturdays since 1939, including on 2 September that year, due to the outbreak of World War Two.
The last time there was a Saturday sitting was 3 April 1982, due to the invasion of the Falkland Islands.
Talks are ongoing between the UK and EU after Mr Johnson submitted new proposals for a Brexit deal, cent red on replacing the Irish backstop – the policy negotiated between Theresa May and the EU to prevent a hard border returning to the island of Ireland.
The UK’s chief negotiator, David Frost, will meet European Commission officials later – but sources say technical talks had effectively reached the limit of what they could achieve.
French President Emanuel Macron has told Mr Johnson the EU will make its final position clear on the chances of a deal by the end of this week.