The 20 Uighurs were being expelled because it was determined they entered the country illegally, Foreign Ministry spokesman Koy Kuong said. He said two other Uighurs are missing.
The United States and United Nations urged Cambodia to stop the deportation. A spokeswoman for the U.N. refugee agency said it had not finished evaluating the Uighurs, including two children, for refugee status.
Cambodia has been under intense pressure from China, which has called the ethnic Uighurs criminals after they fled the country with the help of a secret network of missionaries. The threat of expulsion comes a day before Chinese Vice President Xi Jinping visits Cambodia as part of a four-country tour.
Interior Ministry spokesman Lt. Gen. Khieu Sopheak said the Uighurs would be expelled sometime in the next week.
"I can't say where they will be sent, but I assume their final destination will be China, where they come from," he said.
Some countries have refused to send Uighurs - such as ones released from U.S. detention at Guantanamo Bay in Cuba
- back to China over concerns about retribution and abuse.
Tensions between majority Han Chinese and the Turkic Uighurs in their traditional homeland in far western China exploded into rioting in July, the country's worst communal violence in decades. The Chinese government says nearly 200 people, mostly majority Han Chinese, died.
Uighurs say Beijing has long restricted their rights, particularly clamping down on their practice of Islam. Amnesty International warned in an open letter Tuesday that the Uighurs would be "vulnerable to torture and other cruel, inhuman or degrading treatment or punishment," if returned to China.
Exile groups say Uighurs have been rounded up in mass detentions since the rioting. China has handed down at least 17 death sentences
- mostly to Uighurs - over the violence.
The Uighurs arrived in Cambodia in recent weeks and had initially been in joint custody of the U.N. refugee agency and Cambodian authorities. Khieu Sopheak said they were now under the "sole protection" of the Cambodian government.
Uighur exile groups said daily telephone contact with the Uighurs had been lost.
An evaluation of the Uighurs for possible refugee status had not yet been completed, said Kitty McKinsey, spokeswoman for the United Nations High Commissioner for Refugees in Bangkok.
