BEIJING, Sept 30 (AFP) - China's Premier Li Peng welcomed Tibet's six-year-old Panchen Lama to National Day celebrations in the capital Monday in a further attempt to stamp authority on Beijing's choice for Tibet's second highest religious figure.

According to state television, Li and a number of other high-ranking Beijing officials who are all officially atheist -- received white silk scarves, known as hada, from the newly enthroned boy.

Li urged him to study hard and build on his patriotism to the motherland.

Gyainsain Norbu was selected by Beijing authorities as the 11th Panchen Lama last year, shortly after the exiled Dalai Lama named another six-year-old as the true reincarnation of the 10th Panchen Lama.

Beijing has gone to great pains to justify its own choice, but the move sparked international concern over religious repression in Tibet and over the safety of the Dalai Lama's choice.

In May, a high-ranking Chinese diplomat confirmed the Dalai Lama's choice was under protection from Chinese authorities to stop possible kidnapping from Tibetan separatists.

Earlier Monday, two Chinese dissidents made a rare call for the government to start talks with Tibet's exiled leader, the Dalai Lama, and allow Tibetans the right of self determination.

In an open letter addressed to both the Chinese and Taiwanese governments, the pair broke a long-term taboo, even among dissident circles on the mainland, by questioning Chinese sovereignty over the troubled mountain region.

Wang Xizhe, a veteran pro-democracy activist from Guangzhou and Li Xiaobo, a former history professor at Beijing University, alleged that even the Communist Party had supported Tibet's right to be an independent state before it came to power in 1949.

"We urge the Chinese Communist Party to recognize their earlier position and advance enlightened policies on the right of self determination," they said in their letter, which was faxed to AFP by the Hong Kong-based Information Centre of Human Rights and Democratic Movement in China.

The pair also called on the government to start talks with the Dalai Lama, who has been the focus of vicious verbal attacks from Beijing.

The most recently published attacks against the Dalai Lama called for Tibetan cadres to criticize the exiled spiritual leader without reserve and "fight tooth and nail" against his "criminal" plots to split China.

Neither Li nor Wang could be reached for comment Monday. Those who answered the telephone at Li's home insisted he had never lived there, while the line was cut during a telephone conversation with Wang, and contact could not be resumed.

China'a army invaded Tibet in 1951 and the Dalai Lam fled to India in 1959 after an abortive uprising.