Several MPs have signed an Early Day Motion against gay conversion therapy to ensure that “NHS medical professionals cannot inflict this cruel treatment on their patients”.

The discredited medical practice has been described as “harmful” by the government – although some therapists still seek to provide the treatment – through referrals by GPs.

The Chair of the All-Party Parliamentary Group on Equalities, Labour MP Sandra Osborne, has tabled a motion along with Conservative MP Crispin Blunt and Liberal Democrat MP Stephen Gilbert.

It states: “This House believes that being lesbian, gay or bisexual is not a disease or illness and that therapy which attempts to cure or change a person’s sexual orientation is both ineffective and potentially extremely harmful.”

The motion “calls on the government to investigate any NHS links with conversion therapists, ensuring that NHS medical professionals cannot inflict this cruel treatment on their patients and to take steps to ban conversion therapy for under-18s.”

25 MPs including Conservative backbencher Sir Peter Bottomley and Labour veteran Sir Gerald Kaufman have announced their support for the motion.

Writing for PinkNews.co.uk last month, Diane Johnson, the Labour MP for Kingston upon Hull North, said: “Parliament, and the government, needs to give the issue of conversion therapy much more attention than it has thus far. There hasn’t been a single Select Committee investigation, House of Commons Library publication nor indeed any government statement whatsoever on conversion-related issues.”

Last September, Lib Dem Health Minister Norman Lamb stated that the government had “no plans to introduce statutory regulation for psychotherapists”.

Lesley Pilkington, the Christian psychotherapist who was found to be providing gay conversion therapy, was struck off by the British Association for Counselling and Psychotherapy (BACP) in the same month.

She was initially found guilty of malpractice by the BACP in July 2011, following an undercover investigation by the journalist Patrick Strudwick, but had subsequently appealed the decision.