Robin Gibb "out of coma and communicating with family"
The 62 year-old, who has colon and liver cancer, contracted pneumonia and lost conciousness last week but has shown signs of recovery.
Doug Wright, his spokesman, said he has now been able to nod and communicate with his family, who have been at his bedside at the hospital in Chelsea, west London.
Mr Gibb's relatives, including wife Dwina, daughter Melissa, 37, and sons Spencer, 39, and Robin-John, 29, have been singing to him, with Mrs Gibb revealing he had cried when she played him the song Crying by Roy Orbison.
Mr 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 was thought his cancer was in remission last month, but the latest deterioration in his health coincides with reports of a secondary tumour.
His twin brother and bandmate Maurice died from the same bowel condition that initially led doctors to operate on Robin.
His younger brother Andy, who was not part of the Bee Gees but a successful singer in his own right, died in 1988 from heart failure, aged 30.
Mr Gibb's music career has spanned six decades.
He last performed on stage in February, supporting injured servicemen and women at the Coming Home charity concert held at the London Palladium.