Veteran broadcaster Sir David Attenborough, 87, has undergone surgery to insert a pacemaker.
A spokesman for the naturalist said he was forced to cancel a sell-out speaking tour of Australia because of the "urgent" procedure, although doctors believed the television star was doing well.
"It's a minor procedure but it meant that he cannot go on a 27-hour flight to Australia," he said. "He's very disappointed that he can't fulfill the tour but it's nothing to be alarmed about. He's seeing his doctor now but he's still his lively self."
News of the procedure was issued in a statement by Lateral Events promoting the tour in Australia, Sir David Attenborough: A Life On Earth.
The company said that it would discuss rescheduling the tour following the surgery, while BBC director of television Danny Cohen also sent a message of support, saying: "We all wish Sir David a full and strong recovery."
Sir David said recently that he had no intention of doing less, saying: "I've been broadcasting for 60 years. I don't want to slow down. Retirement would be so boring."
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