A rights group says three Thai citizens who were accused of insulting the king have disappeared.
Thai Alliance for Human Rights claims there’s no sign of the trio after they were arrested in Vietnam.
However Prawit Wongsuwan, Thailand’s deputy prime minister, denies the activists were in Thai custody.
The incident comes months after two exiled critics of the monarchy were found dead.
Last week Thailand crowned its new king, Maha Vajiralongkorn, in an elaborate ceremony at the Grand Palace in Bangkok.

Venezuela quake death toll nears 3,000 as rescue effort winds down
Eight injured in New York shooting
Trump appears on National Mall for July 4 speech after storm-related delay
Qatar says all maritime activities will resume immediately
St. Petersburg region port, oil terminal hit in Ukrainian drone attack