Senior Conservative MPs have joined criticism of Theresa May’s fresh threat to axe the Human Rights Act after Brexit, one warning it would be a “big mistake”.

Dominic Grieve, a former attorney general, told The Independent that repeal would force British people to head to the human rights court in Strasbourg for justice, where hundreds of cases would “pile up”.

And Andrew Mitchell, the ex-international development secretary, said MPs would refuse to scrap the act because the government had failed to set out anything better – despite years of trying.

They spoke out after a minister revealed the government would decide on the future of the landmark legislation once “the process of leaving the EU concludes”.

A House of Lords committee warned this would cast doubt on pledges to protect the European Convention on Human Rights (ECHR), which was incorporated into domestic British law by the Human Rights Act.

It would imperil human rights if the government intended to break the formal link between the UK courts and the EHCR, warned the committee headed by the barrister Helena Kennedy.

Mr Grieve said: “If there is an intention of replacing the Human Rights Act, it would be an incredibly big mistake and entirely pointless because we would remain adherents to the ECHR.

“It would introduce a new level of complexity for no conceivable benefit for either the government or the public whatsoever.

“It appears a bit desperate. Unless there is a British bill of rights, it would see hundreds of cases from here starting to pile up at the European Court of Human Rights in Strasbourg.”

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Mr Mitchell said: “It is perfectly reasonable for the government to suggest amending or replacing the act, but parliament will expect a clear proposition for something better which improves it.

“So far nothing of that nature has been put forward and I very much doubt therefore that parliament would agree to its repeal.”

David Cameron first floated a new British bill of rights as long ago as 2007, with a background threat to dump the ECHR as well, but no firm policy ever emerged.

The UK said last summer that it would remain in the ECHR, after the EU warned that pulling out would jeopardise a future security deal.

However, the current prime minister tore into the Human Rights Act in 2013, blaming it for the long delay in extraditing hate preacher Abu Qatada to Jordan to face terrorism charges.

In her 2016 Conservative leadership campaign, Ms May said she believed ECHR membership had made it harder to deport terror suspects and criminals.

A Ministry of Justice spokesperson told The Independent: “The UK has a longstanding tradition of ensuring rights and liberties are protected here and abroad – leaving the European Union will not change this.

“The UK is committed to membership of the European Convention on Human Rights and will remain a party to it after we have left the EU.