The BBC's John McIntyre: "The Prince has no intention of being drawn into public debate"

The Prince of Wales was making his annual Christmas visit to the Sue Ryder Home in Cheltenham, Gloucestershire, when he stopped to chat with 36-year-old Karen Drake who suffers from MS.

Prince Charles: Public interest in alternative medicine

The Multiple Sclerosis Society has called for clinical trials to investigate claims that the drug can relieve symptoms of the illness.

The BBC's John McIntyre: "The Prince has no intention of being drawn into public debate"

One sufferer, Adrienne Staniford, said she believed the drug helps her and added that the prince's comment was a welcome boost to the whole debate.

"I do know from experience that the benefits that I derive from it are the fact that the spasms in my arms and legs stopped," she said. "Pain control was great and it gave me much more freedom to do what I wanted to do."

Adrienne Staniford finds the drug relieves her pain

In Switzerland, MS sufferers are free to use cannabis. In Britain they face imprisonment although the courts tend to be lenient.

Doctors have welcomed a recent House of Lords science report recommending they be allowed to prescribe cannabis. But they point out that the drug is still too crude for medical use.

"When purer forms of the drug are available then that would be the time to make it available on prescription to those patients who would derive benefit for it," said Dr Bill O'Neill of the British Medical Association.

The prince's curiosity about cannabis can be linked to his public interest in alternative medicines.

But his aides have made it clear that in no way was he promoting the use of cannabis but simply making an inquiry on its benefits for MS sufferers.

A spokeswoman for Prince Charles said: "The Prince of Wales is aware of the current debate on the issue as to whether cannabis should be available to people suffering from severe pain brought on by MS.

"But he has never spoken publicly on the issue and his is a private view."