Large-scale trials of medical cannabis in the UK will begin "as soon as possible", the department of health and social care has said.
The government's National Institute for Health Research is to oversee the studies - which will look at the effects of the substance on epilepsy sufferers.
The NHS currently only prescribes cannabis-based medicines as a last resort and says "very few people in England are likely to get a prescription" for it.
But some people suffering from epilepsy, multiple sclerosis, or undergoing chemotherapy say the drug can help relieve pain and nausea and should be more easily available in a medical setting.
The treatment is currently in limbo as the NHS commissioning body NICE says there is "insufficient evidence" to recommend full use of cannabis, but that the drug may still be considered by doctors if it is "clinically appropriate in an individual case".
As a result the government has backed the creation of two large-scale randomised controlled trials to provide evidence. It is understood that the details of the trails are still being finalised.
Liberal Democrat Christine Jardine, who has previously tabled a Private Members Bill to legalise medicinal cannabis, told The Independent that people had been waiting too long to gain access to the medicine.
"Families across the UK are waiting desperately for these medical cannabis trials to begin. We’ve seen the huge impact these treatments can have and the way they can give people their lives back," she said.
"The Government have dragged their feet for too long on this. It’s welcome that trials are planned, but they must begin immediately - so we can begin to roll out these treatments as soon as possible."
Health minister Maria Caulfield said: "The National Institute for Health and Care Excellence (NICE) reviewed the best available evidence when developing its guideline on prescribing of cannabis-based medicinal products.
"However, NICE found that current research is limited and of low quality. Observational studies with a small number of patients do not produce results which are sufficiently robust to inform routine clinical or commissioning decisions.
"To develop evidence on medical cannabis, the Department, via the National Institute for Health Research, will be supporting two randomised controlled trials into epilepsy in adults and children.
"The trials will commence as soon as possible and results will be published once the trials have completed and the findings have been peer reviewed."
Medical cannabis can either be smoked or vaporised, or taken as an oil or capsule as part of a more conventional preparation.
The use of cannabis for medicinal purposes is widely legal in the United States, with 37 states currently permitting it as medicine.
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