Cannabis for medical purposes should be a legalised, a cross-party group of UK politicians has recommended.The All Party Parliamentary Group on Drug Policy Reform commissioned neurologist Professor Mike Barnes to review evidence from the around the world and concluded the drug eases chronic pain, nausea and vomiting, particularly during chemotherapy.

The group has called on the Home Office to reclassify herbal cannabis under existing drug laws, from schedule one to schedule four.

The herb comes under the same category as steroids and sedatives and would mean doctors could prescribe cannabis and chemists could dispense it, most likely via a mouth spray which contains two chemical extracts (THC and CBD) derived from the cannabis plant.

Patients might even be allowed to grow limited amounts of cannabis for their own consumption. An estimated one million people in the UK use cannabis for medical reasons.

Caroline Lucas, who co-chairs the group, said: "Many hundreds of thousands of people in the UK are already taking cannabis for primarily medical reasons.

"It is totally unacceptable that they should face the added stress of having to break the law to access their medicine," The Telegraph reported.

Under the current laws in England and Wales, cannabis is not recognised as having any therapeutic value and anyone using the drug could be charged for possession, which has a maximum sentence of five years in jail or an unlimited fine.

Neither the Conservative nor Labour Party officially supports legalising cannabis for medical use while the Home Office says there are no plans to legalise what it describes as a "harmful drug."

A Home Office spokesman said: "There is a substantial body of scientific and medical evidence to show that cannabis is a harmful drug which can damage people's mental and physical health," the BBC reported.

About 24 US states, Canada, Israel and around 11 European countries allow access to cannabis for medical use.