BANGKOK (REUTERS) - A United Nations agency protested Thailand's deportation of two registered refugees to China on Wednesday (Nov 18), saying they should not have been sent back to a country "where their lives can be put in danger".

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

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," Ms Vivian Tan, regional spokesman for UNHCR, told Reuters. "They should not be sent back to a place where their lives can be put in danger."

The refugee agency did not name the activists or their nationalities, but an official at an Immigration Detention Centre in downtown Bangkok gave details of their case.

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

Neither China's Foreign Ministry, or the Canadian embassy in Bangkok offered any immediate response to a Reuters requests for comment.

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 relating to the Status of 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 Mr Sunai Phasuk, Thailand researcher at Human Rights Watch.

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

The Uighurs are a Turkic-language speaking group that calls China's western Xinjian region home.

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