China confirmed Thailand deported 40 Chinese nationals on Thursday, despite human rights organizations and members of the U.S. government called on Bangkok to not repatriate the Uyghur Muslims.

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.

Human rights groups warned that the Uyghurs, who were held in Bangkok for more than a decade, will face mistreatment from Chinese authorities back in Xinjiang.

Rights groups criticized the Thai government for sending the Uyghurs, a persecuted Muslim minority, back to China where they face the risk of torture and imprisonment.

International standards and human rights principles must be followed, Thailand's prime minister said on Thursday, in response to concerns aired by activists that 48 Uyghurs held for more than a decade had been secretly deported to China.

Forty-eight men have been detained in legal limbo without charge for 11 years after crossing into Thailand as they tried to escape oppression in China.

Thai lawmakers, activists, and lawyers believe a group of Uyghur men detained in Thailand for more than a decade may have been deported to China early Thursday after trucks with covered windows were seen leaving a detention center and China said Chinese citizens had been repatriated from the Southeast Asian country.

Reported move comes as petition is lodged aimed at halting 'cruel treatment' and blocking deportation to China

The 48 asylum seekers are part of a group of more than 300 Uyghur Muslims who fled China’s Xinjiang region in 2014.