Soul diva Amy Winehouse sipped from a glass of red wine and at first looked a bit unsteady on her feet as she appeared in front of a large audience at the Rock in Rio music festival near Madrid on Friday.

Then, as a crowd of what concert organisers said was 40,000 cheered, she kicked off a pair of high stiletto heels in favour of white moccasins, donned a white electric guitar and settled into an intense rendition of some of her best known songs, including Rehab.

The troubled singer delivered a strong vocal performance accompanied by her octet plus two male backing vocalists.

There was no hint of the controversy that saw the Grammy-winning vocal artist scuffle with a fan at the Glastonbury festival in Britain last weekend and show up an hour late looking the worse for wear last May in Portugal.

Winehouse did not stay for an encore and was seen leaving the outdoor concert venue by helicopter.

Winehouse's manager, Michael Jobson, told national broadcaster RTVE that the singer had looked forward to singing in Madrid after appearances in Portugal and Hyde Park, London.

English band Jamiroquai followed Winehouse on stage, with Colombian pop singer Shakira topping the bill.

The Police, Bob Dylan, Lenny Kravitz, Alejandro Sanz and Franz Ferdinand were all due to perform over the weekend. Organisers said around 350,000 people were expected to have enjoyed music at the newly inaugurated concert site by the end of the festival.