Bee Gees star Robin Gibb remains in a coma in hospital as fans of the cancer-stricken singer left hundreds of messages of hope for his recovery.

Wife Dwina smiled and son Robin-John waved to photographers as they entered a central London hospital on Sunday.

Emily Harrison, from Nova Scotia, Canada, wrote on Gibb's Facebook page: "Get well, Robin, we don't want to lose another Bee Gee!! All your fans are thinking positive thoughts. May God bless you & all your families."

Robin-John, 29, had been due to premier a collaborative classical work, The Titanic Requiem, with his father earlier this month, but the event went ahead without Gibb due to his poor health.

Other family members, including brother Barry, 65, daughter Melissa, 37, and son Spencer, 39, had also reported to have visited Mr Gibb, who is suffering from colon and liver cancer and pneumonia.

Gibb had surgery on his bowel 18 months ago for an unrelated condition, but a tumour was discovered and he was diagnosed with cancer of the colon and, subsequently, of the liver.

It had been thought his cancer was in remission as early as last month, but the latest deterioration in his health coincides with reports of a secondary tumour.

A statement on the singer's website RobinGibb.com said: "Sadly the reports are true that Robin has contracted pneumonia and is in a coma. We are all hoping and praying that he will pull through."

Gibb's agent declined to comment on reports that the star may have only days left to live.