The United States Embassy in Bangkok on Friday issued a security alert for its citizens in Thailand, a day after the deportation of a group of Uyghurs to China.

The secret deportation by Thailand of dozens of Uyghurs to China that has sparked international condemnation is a diplomatic win for Beijing and a snub to the United States and the United Nations, who had long warned that the men would face torture and imprisonment if they were returned home.

At least 40 Uyghurs have been deported to China,Thai authorities have confirmed, despite warnings from rights groups they could face possible torture and even death. The group is thought to have been flown back to China's Xinjiang region on Thursday, after being held for 10 years in a Bangkok detention centre.