The Rolling Stones look set to be without drummer Charlie Watts for their upcoming U.S. tour.

A spokesman for the drummer said he was unlikely to join the rock band's No Filter Tour, which resumes in St Louis in September, because of an unspecified medical procedure.

In a statement shared by Rolling Stones' Twitter page, the 80-year-old said, "For once my timing has been a little off. I am working hard to get fully fit but I have today accepted on the advice of the experts that this will take a while."

Band members expressed their well-wishes, including guitarist Keith Richards, who tweeted: "This has been a bit of a blow to all of us, to say the least, and we're all wishing for Charlie to have a speedy recovery and to see him as soon as possible."

North American tour dates were first cancelled in 2019 because frontman Mick Jagger needed heart surgery.

Rescheduled dates for 2020 were then canned because of the Covid-19 pandemic. As Charlie did not want further delays, he asked Steve Jordan to stand in for the next set of shows.

Steve, who has played with Keith in side-project the X-Pensive Winos, added: "It is an absolute honour and a privilege to be Charlie's understudy and I am looking forward to rehearsing with Mick, Keith and Ronnie.

"No one will be happier than me to give up my seat on the drum-riser as soon as Charlie tells me he is good to go."