Medicinal use of cannabis should be supported and encouraged, a Suffolk MP has said amid calls for more research into the impact of the drug.

Dr Dan Poulter - the MP for Central Suffolk and North Ipswich - said the current law was an impediment to research, which he said also showed its links with mental health illnesses such as psychosis.

He said the law should be for “public protection but also for public benefit”.

He said that under European freedom of movement laws, cannabis could be brought into the country for medicinal use, yet it was not legal for a UK doctor to prescribe cannabis for medicinal purposes unless it happened to be to treat multiple sclerosis.

He added that the current law could see researchers potentially criminalised for carrying out research that would be legitimate in many other fields of medical research.

“We want to improve our treatment of patients with mental ill health, but to do that we need properly to support the researchers in carrying out their work, and I hope that the whole House [of Commons] can sign up to that,” he said.

He said there was a “clear and compelling case” because of the growing medical evidence and the barriers to research, to consider reclassifying cannabis.”

Dr Poulter was speaking in a debate as sweeping new powers banning legal highs cleared the Commons.

He praised a Conservative former minister who “outed” himself as a poppers user.

Crispin Blunt warned he and many gay men were “astonished” by the Government’s plan, adding respect for the law would “fly out the window” because of the ban.

Home Office Minister Mike Penning told the Commons he has offered a “compromise” which will mean poppers are banned but a review will be undertaken to see if it should be overturned.

A final decision taken by Home Secretary Theresa May and Health Secretary Jeremy Hunt will be made before the summer, Mr Penning said, before the Psychoactive Substances Bill received an unopposed third reading.

The Bill creates powers to make all psychoactive substances illegal with listed exceptions instead of forcing each new legal high to be individually banned as they are created and sold.

It bars the production, distribution, sale and supply of legal highs - imposing a maximum seven-year prison term on convicted offenders.