THERESA May has defended a deeply controversial move that would hand the Tories a majority on key Westminster committees to help ease through its flagship Brexit bill after Labour branded it an "unprecedented power-grab".

Despite the Tories losing their Commons majority in the General Election, the Government has tabled a motion for a vote on Tuesday, which would give the Conservatives control over crucial legislative committees that drive the parliamentary agenda.

Jeremy Corbyn, who has branded the move an “unprecedented attempt to rig parliament,” said on the campaign trail in the Midlands: "The Conservatives didn't win the election. They are the largest party, they don't have an overall majority in Parliament, they've done a deal with the DUP which involved £1 billion of money being spent in Northern Ireland and not in the rest of the country, and they now think they've got the right to give themselves a majority in the committee in Parliament.

"It's not so,” declared the Labour leader. “We're a Parliament, a hung Parliament, and the committees should reflect that and there should be no overall Government majority on the committees.

"They should get what's due to them, which would be the largest number of places, but not a majority," Mr Corbyn added.

But Downing Street insisted its planned move was a "common sense" proposal.

The Prime Minister's spokeswoman explained: "The Government has a majority on the floor of the House, therefore, it is perfectly legitimate that it puts to the House, and thereby MPs, that it should also have a majority in committees.

"These proposals will make sure that detailed technical and secondary legislation can be dealt with in committee as usual, rather than everything having to be done on the floor of the House which would significantly restrict the amount of business parliament can consider at this crucial time.”

She made clear that the Government move was one of practicality, confirming that the Tories’ confidence and supply deal did not include the issue of parliamentary committees.

"In practical terms, the Government's working majority at second reading, report stage and third reading will be at odds with the Opposition's majority at committee stage.

“From our perspective this could mean the Government is forced to reverse the amendments made by a handful of opposition MPs at committee stage, through multiple divisions involving hundreds of members. The effect of this would be unacceptable delays."

The row comes as the Government faces a fierce battle to get its Brexit agenda through Parliament.

Opposition parties, and some Tory MPs, have expressed concern about the sweeping nature of the Repeal Bill, which they say gives too much power to ministers.

Public bill committees - formerly known as standing committees - scrutinise legislation line by line in a low-profile but crucial part of its passage through Parliament.

The proportion of seats allotted to each party mirrors their representation in the Commons, meaning that the Government is normally guaranteed a majority and is able to force its legislation through so long as it can avoid rebellions on its own side.

If committee membership matched the make-up of the Commons, the Government could lose control of a vital element of the legislative process.

In practical terms, what this would mean is that if the Government were defeated in the standing committees, it would have to reverse the changes in the Commons chamber, where it would have a majority thanks to the DUP. However, this would make the legislative process more complicated and lengthy given there are eight Brexit bills planned; notwithstanding the opposition the Government will face in the House of Lords, where it does not have a majority.

The motion tabled by Andrea Leadsom, the Commons Leader, for a vote next week will change the rules to ensure Conservatives have a majority on all the committees.

It states that "where a committee has an odd number of members the Government shall have a majority, and where a committee has an even number of members the number of Government and Opposition members shall be equal; but this instruction shall not apply to the nomination of any public bill committee".

Alistair Carmichael, the Liberal Democrat Chief Whip, said: "With every day that passes, this Government gets further from the basic principles of democracy.

"Next they want to pretend that the election never happened in order to try and ram through a destructive hard Brexit. It is an affront to democracy."