"The nature of the riot is neither an ethnic problem nor a religious issue, but a grave and violent criminal incident plotted and organized by the outside forces of terrorism, separatism and extremism," Vice Foreign Minister He Yafei told a press briefing on the first round of the China-U.S. strategic and economic dialogue.
The violence in Urumqi, capital of Xinjiang Uygur Autonomous Region, had left 197 people dead and more than 1,600 injured. Houses of 633 families were damaged and 627 vehicles were smashed and torched.
Some separatists, including World Uyghur Congress (WUC) president Rebiya Kadeer who flew to the United States on medical parole in 2005, were conducting separatist activities in foreign countries, said He.
"Chinese people know well about their activities and I suppose the U.S. side did so too," He said.
Rebiya Kakeer and her WUC, which was seeking "Xinjiang independence", were believed by the Chinese to be behind the Urumqi riots and a series of protests at Chinese embassies worldwide.
"China and the United States took care of each other's core concerns, which facilitated the sound development of bilateral ties since President Barack Obama took office," He said.
"We noticed that the U.S. government's statements were cautious in general and if this issue is touched upon during the dialogue, I think both sides could discuss in a peaceful manner," He said.
The issue, as well as the Chinese government's measures to protect the life and property, however, was China's internal affair, he said.
The dialogue will be held in Washington, D.C. from July 27 to 28. U.S. Secretary of State Hillary Rodham Clinton and Treasury Secretary Timothy Geithner will join their Chinese Co-Chairs, State Councilor Dai Bingguo and Vice Premier Wang Qishan.