A 16-year-old Tibetan girl died after setting herself on fire, Chinese state media said Monday, as the war-of-words between the government-in-exile and Beijing intensified.

The school pupil self-immolated in the village of Dageri in China's northwestern province of Qinghai, an area with a high population of ethnic Tibetans, just before 7pm (1100 GMT) on Sunday, Xinhua said.

Her body was cremated four hours later and returned to her family, the news agency said, adding that local government officials were investigating.

More than 90 Tibetans have set themselves ablaze since 2009 to protest China's rule of the Tibetan plateau, rights groups have said, with the frequency of incidents increasing sharply in November. Most have died.

According to a partial list drawn up by the London-based campaign group Free Tibet the teenager is among the youngest girls to have set themselves on fire.

Xinhua reported on Sunday that a monk and his nephew had been detained for inciting eight Tibetans to set themselves alight.

The men acted on the instructions of the Dalai Lama, Xinhua said, citing police "confessions and investigations".

A commentary carried by the state-run news agency on Monday said the Tibetan spiritual leader was "blasphemous" and "inhumane" in encouraging people to self-immolate for "his own political goals".

But the Tibetan government-in-exile called on Beijing to prove the allegations by sending an investigative team to its headquarters in northern India.

The Dalai Lama has based himself at the hill town of Dharamshala since he fled from Tibet in 1959 after a failed uprising against Chinese rule.

The Central Tibetan Administration also urged China to open up Tibetan areas, which are currently sealed to the international media.

"If China genuinely wishes to end the self-immolations, instead of resorting to the blame game it should allow unfettered access to international bodies to Tibetan areas to investigate the root causes for these self-immolations," the exile government's premier Lobsang Sangay said in an emailed statement.

Many Tibetans in China accuse the government of religious repression and eroding their culture, as the country's majority Han ethnic group increasingly moves into historically minority areas.

Beijing rejects this, saying Tibetans enjoy religious freedom. The government points to huge on-going investment it says has brought modernisation and a better standard of living to Tibet.