The 61-year-old was at his home in Thame, Oxfordshire, when he felt ill and was taken to hospital with his wife Dwina at his side.
An eyewitness told UK newspaper the Daily Express: 'An ambulance rushed over to pick him up. His wife was with him and she obviously looked very worried. He looked in severe pain.'
A friend of the star added: 'He would never go to hospital unless he really had to. He is a very brave man. We don't know if it is a recurrence of the previous problem or if it is something else entirely.'
Gibb has suffered from stomach pains for a number of years although it's claimed doctors have not been able to find out the cause.