The British government was on Wednesday narrowly defeated in a key vote in Parliament on the European Union Withdrawal Bill, the BBC reported. The Theresa May government was defeated 305-309 in the House of Commons after 11 MPs from the ruling Conservative Party cross-voted.

The Tory MPs backed an amendment to the Bill that would require the legislature to approve any Brexit deal made between the United Kingdom and the European Union by a separate Act of Parliament. The Theresa May government had argued that this would jeopardise Britain’s chances of a smooth exit from the European Union.

On Wednesday, 11 Conservative MPs voted in favour of the amendment despite last-minute concessions by ministers and pressure from whips in the ruling party, The Guardian reported. Of those ruling party legislators who voted for an amendment, eight are former ministers. One of them, vice chairperson of the Conservative Party Stephen Hammond, was immediately sacked from his post.

Jeremy Corbyn, the leader of the main opposition Labour Party, described the result as “a humiliating loss of authority for the government on the eve of the European Council meeting”. “Theresa May has resisted democratic accountability,” he added. “Her refusal to listen means she will now have to accept Parliament taking back control.”

But Justice Minister Dominic Raab said the result of the vote would not hold up the Brexit process. “It’s not going to stop us leaving the European Union in March 2019,” he said.