Rock guitarist Brian May has revealed he is having urgent tests for cancer after suffering from agonising back pain.

The 66-year-old star of Queen — who had a knee replacement earlier this year — said he was in so much agony it affected his ability to stand.

He was sent for further tests by doctors after initial MRI scans revealed “abnormalities in the bones”.

Writing on his website on Monday, May said he was about to have another scan but felt “cautiously optimistic” as no sign of cancer had yet been revealed.

He said: “Around Christmas I’ve been having a succession of blood tests, ultrasounds and various kinds of scans to see if they could rule out various kinds of cancer.

“Now, on hearing the ‘C’ word something happens inside you... of course. I’ve seen so many of my dear friends fighting it... and my dad lost his battle at age 66, exactly the age I am now. So over the last few days I’ve been in various states of unrest. But the great thing has been that the team my GP assembled to check out the possibilities has moved Heaven and Earth to gather all the information I need quickly over the Christmas period ... not an easy time.”

May, who has led a campaign against the culling of badgers in recent years, said he started to get “bad pains in the backside” three months after having knee replacement surgery in August.

Thanking his fans for their messages of support, he said: “I’ve been overwhelmed by the amazing messages you’ve been sending me, folks, since I wrote about my ‘Health Scare’.

May said he would continue to prepare for a forthcoming tour as he waited for the results.

He said his doctors were “really positive” and told him that even if tests did reveal cancer, it would be “almost certainly treatable with success”. The musician, who also has a PhD in astrophysics, has said he would rather be remembered for his activist work than for being a rock star.