Visiting Chinese Vice-President Xi Jinping thanked Cambodia for deporting 20 Muslim asylum-seekers while handing the country $1.2 billion US in aid, a government spokesman said Monday.

The 20 ethnic Uighurs deported Saturday had been sought by China in connection with violent anti-government protests by Muslims in western China. Human rights activists are concerned about their fate.

"China thanked the government of Cambodia for assistance in sending back those people to China because under Chinese law these people are criminals. This represents co-operation by the two sides," Cambodian government spokesman Khieu Kanharith said after a meeting between the Chinese vice-president and Cambodian Prime Minister Hun Sen.

He said 14 agreements totalled $1.2 billion US in grants and loans, ranging from Chinese help in building roads to assistance in repairing Buddhist temples. Earlier, China had provided Cambodia with $930 million US in loans and other aid.

Cambodia said it was expelling the Uighurs because they had illegally entered the country.

The United States said Sunday it was "deeply disturbed" by the forcible deportations. State Department spokesman Gordon Duguid said the incident would affect Cambodia's relationship with the U.S. and its international standing.

Cambodia was Xi's last stop on a four-nation Asian tour that also included Japan, South Korea and Myanmar.

Japan and South Korea are rivals to China, while Myanmar and Cambodia are two of the poorest countries in Southeast Asia, where China's government uses its wealth to spread its influence.