Several shops near the Jokhang and Romogia monasteries and the Chomsigkang market have been set on fire.
Chinese troops have blocked roads to the three main monasteries in an attempt to prevent monks from taking to the streets with police using tear gas to disperse demonstrators.
The number of people injured in the protests, which began Monday, is still unknown, although local medics report dozens of wounded. Two monks attempted to commit suicide while others have started hunger strikes.
Beijing officials declined to comment on the situation.
Buddhist monks staged a series of demonstrations to highlight the situation in Tibet in the run-up to the Beijing Olympics and to mark the 49th anniversary Monday of the 1959 uprising against Chinese rule, which led to the exile of Tibet's spiritual leader, the Dalai Lama.
Earlier Chinese foreign ministry spokesman Qin Gang called the riots "a political scheme staged by the Dalai clique," aimed at disrupting "the normal harmonious, peaceful life of Tibetan people."
However, he said that the situation in the Tibetan capital was 'stable.'
