Singer Natalie Cole has blasted Amy Winehouse saying she did not deserve her Grammy awards.

The Unforgettable singer, who has admitted using drugs, says Winehouse is being rewarded for her "bad behaviour".

"I don't think she should have won," Cole, the daughter of Nat King Cole, told a US magazine.

"It sends a bad message to young people trying to get into this business, trying to do it right and keep themselves together."

Winehouse, 24, won five Grammys on Sunday, including record of the year, song of the year and best new artist.

She also thrilled the crowd in Los Angeles with performances of You Know I'm No Good and Rehab live via satellite.

But Cole, who scooped the first of her eight Grammys in 1975, told People magazine she was not a worthy winner.

"We have to stop rewarding bad behaviour," the 58-year-old said.

"I think she is gifted, her performance was fine. I just feel she's stepping into a place she hasn't earned yet."

Winehouse, whose husband Blake Fielder Civil is in jail accused of trying to pervert the course of justice, is undergoing medical treatment for drug addiction in England after a newspaper published photos of her apparently smoking crack cocaine.

"She could die," Cole said. "This isn't something that's cute and fun to throw around in the press.

Those of us who have been in the business long enough know the sacrifice it takes. You don't just get to do your drugs and go on stage and get rewarded."

Cole described her own drug battle in 2000 autobiography Angel On My Shoulder, and confessed to using LSD, heroin and crack cocaine. She entered rehab in 1983 and overcame her problem.