The three activists were allegedly sent back to Thailand, but Thai deputy prime minister denies they are in custody.

Three Thai activists facing charges of insulting the monarchy have disappeared after reportedly being arrested in Vietnam, months after two exiled critics of the military and monarchy were found dead, rights groups have said.

Chucheep Chiwasut, who broadcasts political commentary to Thailand from exile, and fellow activists Siam Theerawut and Kritsana Thapthai were reportedly turned over to Thai authorities by Vietnam on May 8, Human Rights Watch (HRW) said in a statement.

“Vietnam’s alleged secret forced return to Thailand of three prominent activists should set off alarm bells in the international community,” Brad Adams, HRW’s Asia director, said.

Amnesty International said Chucheep had long faced charges of lese majeste, or insulting the monarchy. Siam and Kritsana were also under police investigation for lese majeste, the rights group added.

Article 112 of Thailand’s criminal code says anyone who insults the king, queen, heir or regent faces a punishment of up to 15 years in prison.

The Thai Alliance for Human Rights (TAHR), which is based in the United States, reported in a YouTube video that Chucheep, also known as Uncle Sanam Luang, had been sent back to Thailand.

“Uncle Sanam Luang and two others were apprehended … a month ago. But they were just transferred to Thailand on May 8 from Vietnam,” TAHR‘s Piangdin Rakthai said in the video.

Prawit Wongsuwan, Thailand’s deputy prime minister, denied the three activists were in Thai custody.

“Vietnam has not coordinated transfers. We have not received any request. If there is, it would be through the foreign ministry and police,” Prawit told reporters.

Concrete-stuffed bodies

Human rights groups have accused the ruling military of using the lese majeste law as a way to silence critics.

HRW’s Adams urged the Thai government to disclose the whereabouts of the activists and allow their family and lawyers to see them.

“Only by publicly affirming that these three activists are in detention and in contact with their relatives and legal counsel will the authorities put to rest the fear that these men have been forcibly disappeared,” he said in a statement.

In January, the concrete-stuffed bodies of two exiled critics of the military and the royal family – Chatcharn Buppawan, 56, and Kraidej Luelert, 46 – were discovered along the Mekong River border with Laos.

The military said at the time it had no information about the bodies.

Activist Surachai Danwattananusorn, 78, who operated an online radio station critical of the military government and monarchy from Laos, disappeared in December. His whereabouts are not known. Chucheep and his two colleagues moved from Laos to Vietnam after Surachai disappeared, HRW said.

“We are worried about the situation,” TAHR‘s Piangdin said in his video.

“There have been disappearances and deaths of political activists who are against the military government and criticise the monarchy.”