LONDON (REUTERS, AFP) - No one knows what will happen if Britain's parliament rejects the Brexit deal the government has reached with the European Union, Prime Minister Theresa May said on Monday (Nov 26).

After reaching a divorce deal on Sunday, May is now seeking to win over critics in her own Conservatives and opposition parties who have threatened to vote against it when parliament is asked to approve the agreement.

"There is a choice which this house will have to make. We can back this deal ... or this house can choose to reject this deal and go back to square one," May told Parliament.

"Because no-one knows what would happen if this deal doesn't pass, it would open the door to more division and more uncertainty, with all the risks that will entail."

In response, Labour opposition leader Jeremy Corbyn said the Brexit deal agreed by EU leaders is an "act of national self-harm", while addressing the UK parliament on Monday.

"It's an act of national self-harm... For the good of the nation, the House has very little choice but to reject this deal," Corbyn said.