"Toxicology results returned to the Winehouse family by authorities have confirmed that there were no illegal substances in Amy's system at the time of her death," a spokesman for Winehouse said. "Results indicate that alcohol was present but it cannot be determined as yet if it played a role in her death."

The soul singer, famed for her beehive hairstyle and erratic behavior on and off stage, was found dead at her London home on July 23. The Grammy-winning star behind acclaimed album "Back to Black" had a history of drug and alcohol abuse, and it was widely assumed that they played a part in her death.

Legendary singer Tony Bennett -- who recorded a duet with Winehouse in what was her final session -- will pay tribute to the singer at Sunday's MTV Video Music Awards show in Los Angeles, organizers announced.

Bennett, 85, will introduce footage from the recording session in London in March, where the two sang the duet "Body and Soul". The duet will be released as a charity single in September.

Winehouse's father Mitch said the family was honored by the MTV tribute.

Mitch Winehouse said at his daughter's funeral last month that Winehouse was "the happiest she had been for years" and had conquered her drug addiction three years ago but was trying hard to deal with her drinking.

An inquest into the "Rehab" singer's death is due to resume on October 26 in London.

Winehouse's last filmed performance was in Serbia in June, when she was jeered by the crowd as she struggled to perform her songs and stay upright. Her management then canceled all her scheduled performances.

Mitch Winehouse has announced plans to launch a foundation in his daughter's name to help young people battling addiction. He said however his efforts had been frustrated by "cyber squatters" who had snapped up possible internet addresses for the charity.