Brexit is on course for a lengthy delay after MPs rejected Theresa May's EU Withdrawal Agreement by a margin of 58 votes.
In dramatic scenes in the House of Commons, MPs voted by 344 to 286 against the deal as hundreds of protesters staged a noisy demonstration outside on the day when the UK was due to leave the European Union.
The result of the crunch vote means that the UK has missed an EU deadline to secure an extension of the Brexit process and leave with a deal on May 22.
Mrs May now has until April 12 to go back to Brussels with new proposals and seek a longer extension to the negotiation process, or see the UK leave without a deal that day.
With a clear majority in the Commons against no-deal, and with MPs once more seizing control of the timetable on Monday, Mrs May said that the UK would have to find "an alternative way forward".
This was "almost certain" to involve the UK having to stage elections to the European Parliament in May, she said.
Mrs May said that the outcome was "a matter of profound regret"