BANGKOK — Dozens of Uyghur men detained in Thailand after fleeing China may have been secretly deported to their home country, activists and rights groups said on Thursday, warning they could face torture and imprisonment on their return.

The 48 men were arrested by Thai authorities 11 years ago after crossing the border to Thailand in an attempt to escape persecution in China and had been kept in detention and legal limbo ever since.

On Thursday Thai opposition lawmaker Kannavee Subsang cited unspecified reports suggesting it was “very likely” the group had been sent back to China on Thursday morning.

Subsang posted images on his Facebook page showing six vans with covered up windows, leaving the Bangkok immigration center where it was believed the group had been held.

Arslan Hidayat, an activist working with Justice for All’s Save Uyghur campaign, told CNN that he had been in regular communication with one of the detained men, but had not heard from him since Monday morning local time.

“I did expect a message, so when nothing came through I tried calling and messaging him but no reply,” he said.

China’s repression of Uyghurs and other predominately Muslim ethnic minorities in its far western region of Xinjiang has been labeled “genocide” by the US and other countries, with widespread and credible reports of arbitrary detention, mass surveillance, forced labor and restrictions on movement – allegations China vehemently denies.

Chinese state news agency Xinhua said that 40 Chinese nationals who had illegally crossed the border into Thailand were deported and repatriated to China on Thursday.

The report, which cited the public security ministry, did not mention the deportees’ ethnicity or other identifying details.

“The Chinese citizens deported this time were lured by criminal organizations, illegally exited the country, and subsequently stranded in Thailand,” the ministry said in a written Q&A.

Thailand’s Prime Minister Paetongtarn Shinawatra did not confirm any deportations had taken place when asked by reporters.

“In any country in the world actions must adhere to the principles of law, international processes, and human rights,” she said.

Thailand’s national police commissioner Kitrat Phanphet also declined to comment on the reports, citing security reasons, according to Thai PBS World, a public service broadcaster.

Thailand is not a party to the 1951 Refugee Convention and does not recognize the concept of asylum. The Southeast Asian kingdom has a history of pushing refugees back across its borders and of deporting dissidents.

In 2015, Thailand deported 100 Uyghurs to China, sparking international outcry. The fate and whereabouts of those returned are unknown, UN experts said last year.

Human Rights Watch said “approximately 40” Uyghurs had been transferred by the Thai government to Chinese officials in Bangkok, who then sent them to China, without citing a source.

“Thailand’s transfer of Uyghur detainees to China constitutes a blatant violation of Thailand’s obligations under domestic and international laws,” Elaine Pearson, Asia director at Human Rights Watch (HRW) said.

“The men now face a high risk of torture, enforced disappearance, and long-term imprisonment in China.”

The World Uyghur Congress, an international advocacy group, on Wednesday called on Thailand’s government to “immediately halt the planned deportation of 48 Uyghur refugees to China,” with the group claiming the deportation was planned for Thursday.

US officials expressed “deep concern” over the reports.

“These individuals face a credible risk of imprisonment, torture, or death upon return to a regime that has systematically persecuted Uyghurs through mass internment, forced labor, and other grave abuses,” said John Moolenaar and Raja Krishnamoorthi.

The detained men were part of a larger group of about 350 people detained in 2014, some of whom were minors, according to previous reports from UN experts, rights groups, and Uyghur campaigners.

Five Uyghur detainees, including a newborn and a 3-year-old, have died in detention, the reports said.

In early January, activist Hidayat shared a voice note from one of the detainees, who said the men had been on hunger strike since January 10 in a desperate protest against deportation.

The detainees have said they wish to be sent to a third country and “live in peace” with their families.

Among the prominent voices adding pressure on Thailand was US Secretary of State Marco Rubio, who told his Senate confirmation hearing ahead of being sworn in that he would lobby Bangkok against deporting the Uyghur men. — BBC