Robin Gibb is recovering in hospital after a blood transfusion
The Bee Gees star was in an unnamed medical facility after undergoing the procedure, part of his continuing recovery from colon and liver cancer.
The 62-year-old singer had been due at a London fundraiser for a memorial to the RAF`s Bomber Command, but had to cancel to go to hospital.
A source told The Sun newspaper: "Robin had an operation about three weeks ago and this was a follow-up. He is due to be signed out again shortly."
Robin has made a miracle recovery after undergoing seven rounds of chemotherapy since he was diagnosed 18 months ago, but also said he wonders if his family tragedies - including the deaths of his brothers Andy in 1988 and Maurice in 2003 - are a "karmic price" for the band`s worldwide success.
He said: "I sometimes wonder if all the tragedies my family has suffered, like Andy and Maurice dying so young and everything that`s happened to me recently, is a kind of karmic price we are paying for all the fame and fortune we`ve had.
"But we`ve worked hard for everything we`ve achieved.
"I am not and never have been at death`s door. But the illness, and the untimely death of my brothers, has made me conscious of the fact that - rather than just think about it - it`s crucial that you do today what you want to do."
Robin - who also has a sister Lesley and brother and fellow Bee Gee member Barry - also admits the death of his twin, Maurice, from complications resulting from a twisted intestine, is something he will never recover from.
He said: "How did I get over Maurice`s death? I didn`t. And I never will. I just don`t accept it. I tell myself he`s away on a long holiday and that we`ll be seeing each other again soon."