The lawyer’s Frankfurt firm said he was giving up his defence mandate, but the girl band’s entertainment attorney Christian Scherz issued a statement claiming the man, Achim Groepper, had never been given legal permission to represent Benaissa.

According to Scherz, Groepper’s retreat was the result of an explicit charge from 26-year-old Benaissa that he had never been permitted to speak on her behalf or take legal action for her.

Earlier reports indicated that Groepper had represented the singer since Wednesday,

when Ger Neuber, spokesman for the state prosecutor in Darmstadt said: “We are trying to find a solution to this investigative custody situation with the defence.”

The singer was arrested last Saturday night in Frankfurt shortly before she was due to go on stage at a disco.

The prosecutor says she had unprotected sex with three men between 2004 and 2006 when she knew she was HIV positive, but did not tell them of her status. At least one of these men is now also HIV positive and has accused her of giving him the virus.

Schertz had criticised the information about Benaissa’s HIV status having been released by the state prosecutor. He said the argument for keeping her in custody – that she might otherwise reoffend – had been made irrelevant by the fact that everyone in the country must now know of her HIV status.

Neuber said the authorities had no other choice but to arrest her at the disco, having tried to make contact with her previously to no avail. He also said they felt duty-bound in the light of the massive media interest in the story, to release facts on the state of the matter.

It is unclear how long the singer could remain in custody.