Britain's Parliament voted to avoid an economically disastrous no-deal split from the European Union, opening the door to delaying Brexit and radically re-writing the terms of the divorce.

The House of Commons voted 321 to 278 to reject leaving the EU with no deal and is now expected to seek to delay Brexit in the hope of securing a better deal, which markets would welcome.

Speaking in the Commons, Prime Minister Theresa May said Parliament must now face up to the consequences of its decisions. She announced that if a deal can be agreed to in the coming days, she would ask the EU for a short "technical" extension to the March 29 exit day deadline. If there's no deal, the delay will be much longer, she said.

It is almost three years since Britain voted to cancel its 40-year membership of the EU and with just 16 days to go until exit day, Theresa May's government has failed to get an agreement that can win the support of Parliament.

The prime minister's preferred deal, which took two years to negotiate, was resoundingly rejected by the Commons for the second time in a vote on Tuesday night. Now, MPs have decided to avoid leaving the bloc without a deal.

The question is, what kind of deal will Parliament vote for, and how much longer do Britain's politicians need to make up their minds?

On Wednesday, the EU's chief Brexit negotiator, Michel Barnier, warned that postponing Brexit won't be straightforward.

"It could be a tactical, a political prolongation," Barnier told Euronews TV. "In that case, I know the answers and the reaction of the EU side, the EU leaders, the EU Parliament: 'What for? Why do you need a prolongation? Is it for organizing a new referendum, new elections or not?"'