Sombath Somphone: US concern over missing Laos campaigner
US Secretary of State Hillary Clinton has urged Laos to investigate the disappearance of a well-known social activist who went missing last month.
Security camera footage shows Sombath Somphone being taken away by unidentified men after he was stopped by police in the capital Vientiane.
Rights groups fear that he was abducted by elements associated with the Communist authorities.
But the government in Laos says it knows nothing of his whereabouts.
Although he is not a political figure, Mr Sombath was a prominent campaigner who promoted fair land rights for small farmers, which is a sensitive issue in Laos, the BBC's Nga Pham reports from Bangkok.
"We call upon the Lao government to pursue a transparent investigation of this incident and to do everything in its power to bring about an immediate and safe return home to his family," Hillary Clinton urged in a statement.
Laos is one of the world's few Communist countries where all land belongs to the state - and there have been complaints about land grabs and abuses by local government, our correspondent reports.
Last week three lawmakers from Indonesia, Malaysia and the Philippines visited Vientiane and concluded that they were not satisfied with explanations they had received about the disappearance from officials.