Cigarettes and crack cocaine have given Amy Winehouse early stage emphysema.

And the 24-year-old may need to begin using an oxygen mask if she doesn't stop smoking, her father believes.

The soul singer collapsed at her home on Monday and was rushed to a London hospital to undergo tests. She has remained there all week.

"The doctors have told her if she goes back to smoking drugs it won't just ruin her voice, it will kill her," Mitch Winehouse told The Sunday Mirror.

"There are nodules around the chest and dark marks. She has 70 percent lung capacity."

Doctors have also determined that the Grammy winner has an irregular heartbeat.

Winehouse, a taxi driver, remained concerned for his daughter but said that her work sometimes helped her stay off drugs.

"She could have been dead by now" if she hadn’t played recent concerts in Portugal and Moscow, he said.

"When she's been inactive work-wise then that's when the problems really start. The doctors have said that medically there isn't any reason why she can't do Glastonbury," he explained.

The 'Rehab' singer is due to perform at the Glastonbury festival on Saturday, as well as Nelson Mandela's 90th birthday concert in London on Friday, but her hospitalisation has cast doubt over her participation.

Winehouse senior also asked her drug-using friends to keep their distance. The singer has recently been spending time with convicted drug addict Pete Doherty.

"What hope does she have if people are taking drugs around her," he said.