VINCE Cable’s Liberal Democrats will seek to block Theresa May’s “banana republic power-grab” to secure the Tories majorities on Westminster committees in a bid to push through a hard Brexit.

The Prime Minister’s attempt to change the rules to ensure there are inbuilt Tory majorities on so-called public bill committees, which will scrutinise the Withdrawal Bill and seven other Brexit bills, has caused fury among opposition parties, which believe the Government is undermining Britain’s parliamentary democracy.

Mrs May strenuously denied that she was seeking a power-grab, saying: “No. What we are doing is ensuring the Government's working majority is available across the business in Parliament."

She went on: "We have a working majority in Parliament; you just have to look at the fact we have got various pieces of legislation already, we have already been getting business through.

"We have a working majority in Parliament and it's important that that working majority is covered in all the aspects of work that Parliament does."

Earlier, Downing Street said the issue of securing majorities on the parliamentary committees did not form part of the Con-DUP deal, which gives Mrs May’s minority government a working majority of 13 in the Commons.

A spokeswoman stressed that the Government’s motion, due to be voted on on Tuesday, was a “common sense” move.

She explained: “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."

But the Liberal Democrats will put down an amendment to reverse the Government’s proposed changes to the scrutiny committees and keep the current procedure, in which the political make-up of committees reflects Parliament as a whole.

"Liberal Democrats will work with other parties to resist this attempt to undermine British democracy in the service of an extreme Brexit,” declared Sir Vince.

"Eroding democratic institutions and rigging the rules in your favour is something we'd expect from a banana republic, not a Conservative government.

"Theresa May promised to act with humility and listen to the message sent by the British people after she lost her majority. It is now up to MPs to hold her to that promise and prevent this shameful power grab,” he added.

Jeremy Corbyn, continuing his summer campaign trail in the Midlands, insisted: "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. We're a Parliament, a hung Parliament, and the committees should reflect that and there should be no overall Government majority on the committees.”

The Labour leader added: “They should get what's due to them, which would be the largest number of places, but not a majority."

The SNP’s Patrick Grady said: “Theresa May called the election and she has to respect the result. We are a Parliament of minorities.”

The Glasgow North MP suggested the hardline Brexiteers had “some serious questions” to consider given their core argument in the EU referendum was to return sovereignty to Parliament. “Both the votes [on the Withdrawal Bill and the parliamentary committees] have the potential to undermine seriously the Parliament they have fought for.”

Amid all the political heat, Mrs May is almost certain to secure victories on both of next week’s votes; Monday will see MPs vote on the Withdrawal Bill.

However, pro-EU Tory rebels could cause trouble for the Government at several points during the course of the swathe of Brexit bills in addition to the opposition the PM is set to face in the House of Lords, where the Government does not have a majority, and to the opposition from Holyrood, which is likely to withhold its consent on the flagship Brexit legislation.