Solo Krummah died in hospital over the weekend, his United Democratic Party (UDP) said, its second member to lose his life in custody since the start of a crackdown on opposition protests earlier this year.

There were no details on what treatment had been needed or how he died, the UDP said.

"We deplore the reported death in custody of ... Solo Krummah," UN High Commissioner for Human Rights spokeswoman Cecile Pouilly said in a statement, citing reports that he had been denied medical care "on several occasions while in detention".

"We urge the authorities to investigate the death as well as allegations that detainees are denied access to medical care."

It said the allegations came from detainees themselves.

The statement followed criticism from the US State Department on Tuesday, which said it was "troubled by reports of the Gambian government's continued mistreatment of detained opposition figures, as evidenced by recent deaths and allegations of torture".

Gambia's government spokesman was not immediately available for comment.

Foreign powers and rights groups regularly accuse President Yahyah Jammeh, who has ruled the West African nation of 2million people since taking power in a coup in 1994, of using security forces to stamp out political dissent.

--reuters--