A woman pronounced "very certainly clinically dead" at a French hospital woke up hours later after her sons refused to turn off her life-support system.

Doctors were preparing cancer patient Lydie Paillard, 60, for a chemotherapy session when she passed out, the director of the Bordeaux Rive Droite private hospital Yves Noel told AFP on Wednesday.

A doctor managed to resuscitate her and put her on a ventilator but then, having consulted other doctors, called Paillard's sons to break the news that their mother was "very certainly clinically dead".

But her sons would not turn off the respirator and she was then transferred to the university hospital of the southwestern French city where a scan revealed that she was in fact not brain dead, Noel said.

"It's a kind of miracle," he said of Paillard, who woke up after 14 hours. He said that the doctor who resuscitated her had committed a communication error not a medical one as "he saved her life."

"All I remember is that I felt unwell after receiving an injection to prevent me vomiting," Paillard told AFP by telephone from hospital where she said she felt "more tired than usual" after her ordeal.

"My sons, whom I saw yesterday, explained to me that the hospital wanted to turn off the life support system because it was over and as they refused, I was taken to the university hospital.

"I haven't really realised what's happened but I think my three sons are the most shocked."

The hospital's management said it would suggest the family meet the medical team responsible for Paillard to discuss the "communication problem."