Medicine regulators have been accused of dragging their feet over a cannabis drug for people with multiple sclerosis.

The Medicines and Healthcare Regulatory Agency met last week to discuss Sativex, a medicinal form of cannabis.

It decided that more clinical data was needed before the drug could be approved for widespread use on the NHS for treating muscle stiffness in MS patients.

Professor Mike Barnes, consultant neurologist at the University of Newcastle and a trustee of the MS Trust charity, said: "This decision leaves many people with MS little option but to resort to 'street' cannabis for relief from the painful and disabling symptoms of their condition.

"With Wednesday's announcement by the Prime Minister that re-classification of 'recreational' cannabis is being considered, this is even more worrying."

He said there was compelling evidence that Sativex helped a large proportion of people with MS.

On average, half the patients who tried the drug gained some benefit and there were no concerns about side-effects.

Chris Jones, chief executive of the MS Trust, said: "It is a sad fact that the system imposes a 'one size fits all' model on a condition like MS.

"One size never fits all with MS - it is a hugely variable condition with variable responses to treatments. To deny some patients because the treatment doesn't help everyone is madness."

Mr Jones added: "Sativex meets a currently unmet medical need in patients where there is no other conservative treatment option. It is our view that Sativex should be licensed and become available on prescription."

MS sufferer Pauline Taylor, from Durham City - who has smoked cannabis in the past to relieve her pain - also condemned the delay. "It's disgusting," said the 55-year-old former nurse. "It means people with MS will continue to suffer pain and spasm.

"They don't believe that sufferers have the pain they have got. They don't believe cannabis works. They think you're just pulling their leg."