• Agency warns the two refugees' lives could be in danger
• Two waiting to go to Canada had a UN protection letter
• Men sent back for entering Thailand illegally - Thai authorities

BANGKOK: A United Nations agency protested against Thailand's deportation of two registered refugees to China on Wednesday, saying they should not have been sent back to a country where their lives could be in danger.

The United Nations High Commissioner for Refugees (UNHCR) agency said the two individuals were in possession of a UN "protection letter".

UNHCR said they were waiting to go to Canada, having been accepted as refugees, at the time of their arrest by Thai authorities.

"These people are recognised refugees, meaning they were interviewed and their claim of persecution was found to be legitimate," said Vivian Tan, regional spokeswoman for UNHCR.

"They should not be sent back to a place where their lives can be put in danger."

Thai authorities declined to comment on the protection letter on Thursday, but said the men were sent back because they entered Thailand illegally.

"We have taken every step in accordance with the Thai laws," General Thawip Netniyom, secretary-general of the country's National Security Council, told Reuters.

"All we know is that they appear to be dissidents of the Chinese government. We don't know about their other offences."

In Washington, the US State Department also said the two could be in jeopardy on their return to China.

"We are deeply concerned that Thailand has sent two UNHCR-registered Chinese refugees back to China where they could face harsh treatment, arbitrary detention and the lack of due process," US State Department spokesman John Kirby told a daily briefing.

The UNHCR did not identify the activists or their nationalities, but an official at an Immigration Detention Centre in Bangkok gave details of their case.

Jiang Yefei and Dong Guangping were arrested on October 28 following a request from China, the official, who declined to be named because of the sensitivity of the matter, told Reuters.

Chinese Foreign Ministry spokesman Hong Lei said the issue was being handled "in accordance with the law". He did not elaborate.

Thailand's generals have cultivated warmer ties with China since seizing power in a 2014 coup. The coup was widely condemned by Western nations, which downgraded diplomatic ties, but the ruling junta claimed to have support from China.

Thailand has not signed a 1951 Geneva convention on refugees, nor does it have a specific law on refugees.

"By sending the men back to China, where they could face torture, Thailand is repeating its bad record on refugees," said Sunai Phasuk, a Thailand researcher at Human Rights Watch.

Thailand deported about 100 Uighur Muslims to China in July, drawing condemnation from the United States and others.

The Uighurs are a Turkic-language speaking group from China's western Xinjiang region.

Thai immigration officials said the two deported men were not Uighurs.