U.K. Chancellor of the Exchequer Philip Hammond ramped up the pressure on Brexiteer Tory MPs as he warned they will trigger a long delay to leaving the European Union unless they support Theresa May's proposed deal when it returns to Parliament.

A growing number of Tories are now backing the prime minister's agreement, he said, and the deal will only be put to another vote in the House of Commons this week if the government is confident of victory. The deal was defeated for the second time on Tuesday, and persuading opponents to switch their vote is "a work in progress," Hammond said.

"What's happened since last Tuesday is a significant number of colleagues have changed their view on this, and decided the alternatives are so unpalatable to them that they, on reflection, think that the prime minister's deal is the best way to deliver Brexit," Hammond said in an interview with BBC TV on Sunday. "It's absolutely vital that we get it through next week. It's the final chance to do this deal without having a long extension," he said.