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.

Major quake hits southern Japan, workers missing after mall blast
Trump cites 'good' talks on Iran, reiterates threat to hit targets
France braces for fourth major heatwave, Macron calls situation 'severe'
India's top court orders no coercive action against youth protesters
Trump says US and Tehran having 'good, friendly talks'
