London, July 30 (IANS) Troubled British singer Amy Winehouse's father Mitch is convinced that one of her friends had spiked her drink with the killer drug ecstasy and he wants to find that person.

Winehouse, 24, had to go back to hospital after Mitch found her convulsing, thesun.co.uk reports. At first it seemed that she was reacting to medication that she is taking to fight her drug addiction, but Mitch now thinks the drink was spiked.

He called police to register his suspicions and has warned his daughter that he will find the "friend" who is responsible for this.

A source said: 'Mitch is furious. He's certain someone put E in Amy's drink - and he's determined to get to the bottom of it. He is convinced that one of her hangers-on was responsible and he's waiting for a toxicology report to show what caused her fit.

'If his suspicions are proved right, he wants someone to be punished. He is seriously unhappy about Amy's flat being a stopover for randoms and wants an end to it.'