Petroc Trelawny, who presents several radio programmes for the British public broadcaster, was arrested on Thursday, apparently for taking part in a music festival without a work permit, said campaign group Zimbabwe Vigil.

"He was apparently the only musician without a work permit and that is why they arrested him," said group coordinator Rose Benton. She said she was told about the arrest by her relatives in Zimbabwe.

"He has been in police custody in Harare . pretty nasty business.

"Yesterday was a public holiday. Normally, it would take a day to get him out but he will be in until Monday probably."

Trelawny, in his 40s, was billed to appear at the Bulawayo Music Festival on May 23-27 and had been posting updates on Twitter about his preparations, including rehearsals with children's choirs.

Britain's The Daily Telegraph newspaper reported that he had been led from the stage by immigration officials during a performance at the festival and dislocated his shoulder in a fall in a police cell.

A spokesman for Britain's Foreign Ministry said: "We can confirm the detention of a British national on May 24 in Zimbabwe. We are providing consular assistance."

A BBC spokesman said: "We are aware of the situation and hope it will be resolved quickly."

Zimbabwean jails are notorious for their poor conditions and President Robert Mugabe, 88, who has ruled for 30 years, is decried by activists as one of the worst perpetrators of rights abuses.