LONDON (REUTERS) - A group of senior British lawmakers on Thursday (Nov 29) put forward an amendment to block Prime Minister Theresa May's EU withdrawal deal and to rule out a no-deal Brexit when it comes before parliament for a crucial vote next month.

May must win a vote in parliament on Dec 11 to get her deal approved or risk seeing Britain's exit plans descend into chaos four months before the country is due to leave the European Union on March 29.

Hilary Benn, chairman of parliament's Brexit committee, said he had proposed an amendment to the government's motion on the EU withdrawal agreement and had the backing of senior pro-EU lawmakers from both May's Conservatives and the opposition Labour Party.

"It opposes the deal, rejects a no-deal Brexit ... and would enable the House (of Commons) to express its view about what should happen next if the PM's deal is defeated," Benn, a Labour lawmaker, wrote on Twitter along with a picture of a copy of his amendment.

Parliament will spend five days debating May's deal before a vote. It envisages maintaining close ties with the EU after Brexit but faces opposition from across the political spectrum, from both those who support Brexit and those who oppose it.

The government minister in charge of parliamentary business, Andrea Leadsom, said earlier on Thursday that lawmakers would vote on attempts to alter or thwart Brexit before May's own proposed deal is put to a must-win ballot.

The government announced the schedule and format for the debate late on Wednesday and stated that opponents would have the chance to amend the government's motion that would approve the agreement.