Labour has signalled its intent to vigorously oppose planned changes to parliamentary boundaries, saying the shakeup is politically motivated and aimed at hurting the party at the next general election.

Labour is worst hit by the initial proposals, which are part of an effort to cut the number of MPs in the House of Commons from 650 to 600.

The process could also trigger a battle in which supporters of the Labour leader, Jeremy Corbyn, seek to purge MPs who oppose him.

Plans for new constituencies in England and Wales, announced on Tuesday, show Corbyn, George Osborne and Boris Johnson are among high-profile politicians who will have their seats redrawn.

Other MPs affected include Yvette Cooper, Tristram Hunt and Owen Smith. Labour could lose 23 seats under the revamp, according to analysts.

Jon Ashworth, the shadow Cabinet Office minister leading the process for Labour, said the party was convinced the proposals were motivated by party politics.

“This proposal is certainly about disadvantaging the Labour party in the next general election,” he told BBC Radio 4’s Today programme. “That’s why they’ve gone from 650 seats to 600 – by the way, at the same time stuffing the House of Lords with 260 unelected lords at a cost of £30m, but they don’t tell us about that.”

The boundary commissions for England, Wales, Scotland and Northern Ireland have been tasked with trying to balance the number of registered voters in each new seat. But Ashworth asked why they were told to do so using electoral data from December 2015, before an estimated 2 million new voters signed up before the Brexit referendum.

“If the question is ‘should the constituencies be of equal numbers?’ then we are in favour of the principle of more equal constituencies,” he said. “But what this is doing is proceeding with a boundary review when there’s 2 million people missing from the electoral register. The effect of not using that register is to deny the voice of 2 million people.”

The Boundary Commission for England has insisted there is no political intent behind the proposed changes. “We don’t take into account any effect on the political ramifications of our proposals,” Sam Hartley, secretary to the commission, told Today. “We are not the government and we are not parliament. Our role is to make sure we take an independent view on the boundary proposals.”

Hartley stressed that three rounds of consultation on the plans could lead to significant amendments before the new seats are finalised.

“The boundary commission is very, very good at listening what people have to say,” he said. “In the last review, at the same time, we changed nearly two-thirds of the constituencies from the initial proposal stage to the revised proposals during the process. We are open, and we are listening to what people say.”

Adding to the difficulties for Labour, a member of the party’s National Executive Committee (NEC) has raised the idea of using the shakeup to remove MPs who have not shown loyalty to Corbyn.