Jeremy Corbyn says talks with the government to find a compromise over Brexit "have gone as far as they can".
In a letter to the PM, the Labour leader said the six weeks of cross-party discussions could not carry on due to "the increasing weakness and instability" of the government.
Downing Street has yet to respond.
Labour and the Conservatives are now expected to discuss how to put a number of options to MPs to break the Brexit deadlock in Parliament.
On Thursday the PM promised to set a timetable for leaving Downing Street following a Brexit vote next month.
Environment Secretary Michael Gove said MPs needed to "focus on making sure that we honour [the] mandate" of leaving the EU.
Please subscribe HERE http://bit.ly/1rbfUog