Sir David Attenborough is set to undergo surgery to insert a pacemaker.

The naturalist, 87, has been forced to cancel a sell-out speaking tour of Australia because of the procedure after being advised that he is in "urgent need" of the pacemaker.

In a statement issued by the company promoting the tour, it said the broadcaster was due to undergo the surgery today (June 4).

"Sir David Attenborough is to undergo surgery in London following advice from his cardiologist that he is in urgent need of a pacemaker," Lateral Event Management said. "It is with regret, therefore, that Lateral Events CEO Simon Baggs announced that the forthcoming sell-out tour of Australia, scheduled to begin in Brisbane next week, has been cancelled.

"Sir David expressed his extreme disappointment as he said he was very much looking forward to coming back to Australia and he hopes to reschedule his tour in the near future."

The company said that it would discuss rescheduling the tour, Sir David Attenborough: A Life On Earth, following the surgery.

BBC director of television Danny Cohen said: "We all wish Sir David a full and strong recovery."

Sir David, whose groundbreaking programmes have included Blue Planet and Frozen Planet, recently narrated and presented the hit BBC One series Africa.

He also presented a new BBC Radio 4 series, Tweet Of The Day, devoted to birdsong.

Sir David, who has been named Britain's greatest living national treasure, recently said that he had no intention of slowing down, saying: "I've been broadcasting for 60 years. I don't want to slow down. Retirement would be so boring."