MINISTERS must reform key Brexit legislation to ensure it does not undermine devolution and the Union, a Conservative MP has said.

Paul Masterton, who represents East Renfrewshire, described clause 11 of the European Union (Withdrawal) Bill, which is focused on powers currently held by the devolved administrations, as “not fit for purpose” and said it must be replaced with a new version.

He added progress was being made and he expected further movement at the next Joint Ministerial Committee (JMC) between the UK Government and the devolved administrations, noting the Scottish Conservatives “stand ready to help broker a compromise”.

Mr Masterton outlined assurances he wanted from the UK Government – through the JMC – including that they would identify and agree areas where legislative common frameworks were needed and that other powers could be devolved immediately after Brexit.

MPs heard clause 11 of the bill would set as a default that powers currently exercised by devolved governments within EU frameworks would be returned to Westminster.

The Scottish and Welsh governments have called the bill a power-grab by London on devolved matters, and these warnings were echoed by MPs in the Commons.

Concerns were raised over the bill, which seeks to transfer European law into British law, as MPs continued their line-by-line assessment of it.

Speaking as the bill entered its fourth day at committee stage, Mr Masterton criticised opposition amendments but said his vote with the Government “should not and must not be taken as an acceptance of clause 11 as it stands”.

Mr Masterton said: “Clause 11 as drafted is not fit for purpose and it must be changed. It doesn’t need to be tweaked a little bit, it does need to be amended and replaced with a new version.

“But I do not consider now to be the appropriate stage in the process to demand the new drafting be brought forward before the House.”

Mr Masterton, in response to a question on what action he would take if he does not receive assurances, said: “I’ve said it at second reading, I’ve said it again tonight, I will not support the bill which undermines devolution and does not respect the integrity of the union.”

Shadow Brexit minister Jenny Chapman earlier added that it was “wrong” for the Government to attempt to use Brexit as an excuse to gain powers for London.

Labour’s new clause 64 would establish new UK-wide structures for dealing with retained EU law that would involve the devolved administrations.

The party’s new clause 65 would put the JMC’s role in the withdrawal process on a statutory footing.

“People voted for these powers to be devolved and it is wrong for the Government to attempt to use Brexit as an excuse to gain these powers back to London,” said Ms Chapman.

The SNP’s Westminster leader Ian Blackford told ministers that the clause 11 “completely undermined” the current devolution settlements in place.

Mr Blackford added the bill was the “biggest threat” to the devolved settlement since the Scottish parliament reconvened in 1999.

He said: “As it stands the SNP cannot and will not support it, clause 11 is a bare-naked power grab and completely undermines the devolution settlements across the UK. This bill tramples all over the devolved competencies of the parliaments in Edinburgh, Cardiff and in Belfast.”

Scottish Secretary David Mundell said his characterisation was “pantomime”.