Theresa May must pledge to keep Britain signed up to Europe’s human rights court as part of the next Conservative manifesto, senior Tories have demanded.

They made the plea as part of their year-long inquiry into human rights laws, convened by the Bright Blue think tank, which promotes liberal conservatism.

The inquiry also calls for Sharia councils to be banned from conducting Islamic marriages in the UK if the couple have not previously obtained a civil marriage certificate, as well as legislation that would make it a criminal offence to be party to a forced marriage.

Ryan Shorthouse, the director of Bright Blue, said: “When she was standing to become leader of the Conservative Party last summer, the prime minister promised Conservative MPs that she would abandon her plan to withdraw the UK from the European Convention on Human Rights.

“It is vital that she keeps to her word on this and confirms that any future Conservative government will ensure that the UK remains a signatory of the European Convention on Human Rights.

“The judgments of the European Court of Human Rights have strengthened human rights in Britain, as well as in more oppressive countries.”