THERESA May has been warned she will provoke a constitutional crisis if she takes the UK out of the European Convention on Human Rights (ECHR).

Sources close to the UK Government say the Prime Minister might fight the next General Election on quitting the treaty that guarantees freedoms and human rights.

The SNP dismissed the proposal, saying it was “red meat” for the “baying” right of the Tory party to keep them happy after Downing Street admitted its British Bill of Rights is on hold until after Brexit.

But the SNP added that if the move did go ahead it would need Holyrood’s consent. May would not get that, which would mean a constitutional crisis.

A Government source told The Telegraph the Prime Minister knew she didn’t have the full support of the party to quit the ECHR and wanted a mandate from the people.

“A clean break [from the ECHR] is by far the best option and, if we put it in the manifesto, even those Tory MPs who are squeamish about the idea will have to get behind it,” the source said.

In 1997, the then-Labour Government passed the Human Rights Act, incorporating the ECHR into UK law. That meant the principles of the treaty had to be included in every subsequent Act, including the Scotland Act and the Good Friday Agreement, the framework for Northern Ireland’s devolved government.

That means the highest court in the country is the European Court of Human Rights in Strasbourg. Quitting the ECHR would transfer that role to the British Supreme Court.

Though David Cameron wanted to repeal the Human Rights Act and replace it with a more limited British Bill of Rights, even he never wanted to stop being a signatory to the ECHR. Plans for a Bill of Rights have now been shelved until after Brexit, with Downing Street saying they have “more pressing matters” to deal with.

Professor James Chalmers of the University of Glasgow, said ditching the convention would solve no problems and create more. “UK citizens have had the right to take cases to the European Court of Human Rights since 1966,” he said.

“The Thatcher government, amongst others, expressly chose to maintain that right. Fewer than one per cent of cases taken to the European Court of Human Rights against the UK result in a ruling against the UK Government.

“There isn’t a problem here that needs addressing, and because the ECHR is hardwired into the devolution settlement and especially the Good Friday Agreement, the process of withdrawal and replacement with domestic legislation will most likely tie the Government in knots for years, in all probability achieve nothing of any value, and diminish our influence in promoting human rights abroad.”

May first approached the idea of complete withdrawal in April in the EU referendum campaign. She said the ECHR binds “the hands of Parliament”, “adds nothing to our prosperity” and prevents deportation of “dangerous foreign nationals”.

Even right-wing Brexiteer Michael Gove, then justice secretary, baulked at the idea, saying he would rather remain a signatory to the convention.

A spokeswoman for the Ministry of Justice said: “We will set out our proposals for a Bill of Rights in due course. We will consult fully on our proposals.”

The SNP Home Affairs spokeswoman Joanna Cherry said: “The Tories have a reckless ideological obsession with attacking human rights – but their attempts to leave the ECHR and draw up a so-called British Bill of Rights have been utterly shambolic. These plans are merely an attempt to kick the issue into the long grass while throwing some red meat to Theresa May’s baying backbenchers.

“Human rights are a devolved matter and any plans to take Scotland out of the ECHR would require the consent of the Scottish Parliament. Given the strong cross-party support for the ECHR and the Human Rights Act in both the parliament and across Scottish civil society consent would not be forthcoming ... any attempt to repeal existing rights would be likely to provoke a constitutional crisis.”