China vowed Saturday to "severely crack down on any separatist activities" in Tibet as it launched a new national holiday marking the 50th anniversary of a failed uprising in the Himalayan region.

The Chinese flag was raised in front of the Potala Palace in Tibet's capital Lhasa as more than 13,000 people, most in Tibetan traditional dress, rose for the national anthem to commemorate "Serfs' Liberation Day".

"The red five-star flag will fly forever over Tibet," the region's Communist chief, Zhang Qingli, told the crowd in a colourful ceremony broadcast live across China on state television.

"The struggle between us and the Dalai clique is not an issue of ethics, religion or human rights," he said, referring to Tibetan spiritual leader the Dalai Lama, who fled into exile after the failed uprising in March 1959.

"It's about maintaining national sovereignty and territorial integrity... (we must) firmly stand guard and severely crack down on any separatist activities."

Beijing accuses the Dalai Lama and his administration, now based in northern India, of seeking independence for Tibet but China considers the failed uprising the end of "feudalism" in the region.

China has ruled Tibet since 1951, after sending in troops to "liberate" the Himalayan region the previous year, and Beijing has long maintained that its rule ended a Buddhist theocracy that enslaved all but the religious elite.

Authorities, apparently fearing not everyone shares the celebratory mood, have launched a massive security clampdown in Tibet and neighbouring regions to quell possible unrest related to the uprising anniversary.

Last year, widespread demonstrations and riots erupted in Tibet and other nearby provinces with large Tibetan populations as protesters called for greater religious freedom and autonomy from Beijing's rule.

China's hand-picked choice as the second highest Tibetan spiritual figure, the Panchen Lama, addressed an international gathering of Buddhists in the eastern city of Wuxi on Saturday to mark the holiday.

"For a long time the Dalai's separatist clique has ignored the success of Tibet's development, plotted and planned to ruin Tibet's social stability and wantonly attacked the policies of the central government," he said Friday in a state television interview.

It was the latest in a series of appearances by the 19-year-old Panchen Lama leading up to the holiday, with experts and pro-Tibet groups accusing Beijing of mounting a propaganda offensive against the Dalai Lama.

Years of discussions between the Dalai Lama and the Chinese government over the parameters of "Tibetan autonomy" have not resulted in any significant changes in the nature of China's rule over the region.

President Hu Jintao said Tibet's economy and society can only develop by "staying in the big family of the motherland under the leadership of the Communist Party of China," the official Xinhua news agency reported.

Hu was quoted as saying Tibet should move from being "basically stable" to "peaceful and stable in the long run."