Troubled singer Amy Winehouse stunned followers at the U.K.'s Glastonbury festival after seemingly attacking a fan.

The 24-year-old was singing her hit track Rehab to 75,000 fans on the Pyramid Stage on Saturday when she jumped from the stage and into the security pit.

The star - who has been receiving medical attention for the lung disease emphysema - then appeared to lash out at a fan, striking the unnamed devotee with her fist.

But a spokesman for Winehouse insists she was provoked, adding, "The 'lashing out' was when someone tried to grab her hair and she reacted."

Winehouse also hit back at fans who booed her as she paid tribute to her incarcerated husband Blake Fielder-Civil.

She said, "Boo me one more time and I'll find you and your phone and call your mum and tell her you ain't got no manners."