Qiangba Puncog said that the riots were the result of a conspiracy hatched by domestic and overseas separatists advocating "Tibet independence".
It was "premeditated, organized and masterminded" by the Dalai Lama clique, he said.
"A tiny handful of separatists and lawless elements engaged in extreme acts with the goal of generating publicity to wreck stability during this crucial period of the Olympic Games," he said.
Qiangba Puncog also said he was indignant that some Westerners and the Dalai Lama group had spread a distorted version of the unrest by describing the riots as a "peaceful demonstration".
He said no democratic country would tolerate the brutality shown by the rioters in Lhasa.
Yet he expressed confidence in maintaining social stability and order under the leadership of the central government.
"Any plot to destroy social stability or to mastermind the secession of Tibet are against the will of the people in Tibet and doomed to failure," he said.
Meanwhile, the Foreign Ministry last night condemned the attacks against Chinese embassies and consulates in Europe and the US by Tibetans linked to the Dalai Lama.
Rioters smashed doors and windows at China's embassies and consulates, said spokesman Liu Jiancohao. He urged foreign governments to increase security at Chinese missions.
"The atrocities of the Tibetan independence forces manifested again the splittist nature of the Dalai clique and the hypocrisy and deceit of its peace and non-violence propaganda," Liu said.