The United States expressed "great concern" Monday for the safety of outspoken Gambian religious leader Imam Baba Leigh, who was arrested last month and is being detained incommunicado.
The cleric was arrested on December 3 after criticising President Yahya Jammeh's regime for executing nine death row inmates last year.
The United States is "greatly concerned about the welfare and safety of Imam Baba Leigh," the US embassy in Banjul said in a statement.
"Imam Baba Leigh remains unaccounted for and the government of the Gambia has denied his family the opportunity to visit him," it added.
"We call on all concerned to provide access for the family to Imam Baba Leigh and to treat him fully in accordance with the laws of the Gambia and the accepted norms of international human rights."
One of Baba Leigh's relatives confirmed to AFP on Sunday that the religious leader had not been seen since his arrest.
The European Union has also criticised the cleric's arrest.
Jammeh provoked an international outcry when he announced in August last year that all Gambia's death row inmates would be executed by mid-September. A week later, a first batch of nine were executed by firing squad.
According to rights groups, close to 40 other prisoners faced death but no further executions were reported.
International rights bodies regularly condemn Gambia -- the smallest country on the African mainland -- for rights abuses including arbitrary arrests and detentions of opponents, journalists and rights defenders.
Jammeh, who claims to be able to cure AIDS and other diseases, has ruled the country of 1.8 million people with an iron fist since a coup in 1994.