A COMPANY that develops cannabis-based medicines celebrated a landmark yesterday after receiving preliminary approval for a product in Canada.

GW Pharmaceuticals said Sativex mouth spray could be available on prescription to multiple sclerosis (MS) sufferers in the next few months, sending shares in the company up nine per cent.

It will be the first cannabis-based treatment to receive approval.

The news will be particularly welcome coming only two weeks after UK regulators demanded further testing of the drug, causing shares to lose a quarter of their value.

GW, which grows cannabis plants at a secret location in the UK, is appealing against the decision.

Sativex is a medicinal cannabis extract containing tetrahydrocannabinol and cannabidiol.

Trials have shown it is also effective in treating patients with arthritis.

The company, based in Salisbury, Wiltshire, will now have to complete routine paperwork before Sativex can be prescribed in Canada.

About 50,000 people in Canada and 85,000 in the UK have MS.