Arjia Rinpoche was abbot of one of Tibetan Buddhism's four most important monasteries - the Kumbum monastery in China's Qinghai province - and is known in China as a living Buddha, the reincarnation of a senior Tibetan monk. .

The abbot also held high-ranking positions in the Chinese hierarchy as vice-president of the state-controlled Buddhist Association and a standing committee member of the government-appointed advisory body to China's parliament.

Arjia Rinpoche, is one of the most senior Tibetans to have left the country since the Dalai Lama went into exile in 1959.

Disagreement with government

The Dalai Lama: Tibet's spiritual leader

A source in the Tibetan government-in-exile in India told the BBC that the abbot left Tibet around four months ago, following disagreements over China's religious policies.

In the last couple of years, China has been waging a campaign to purge Tibetan monasteries of Dalai Lama supporters.

China accuses the Dalai Lama, who lives in exile in Northern India, of being a "splitist " intent on gaining independence for Tibet.

Arjia Rinpoche was also a close associate of the late Panchen Lama, who before his death in 1989 was China's highest-ranking Tibetan Buddhist leader.

The BBC correspondent in Beijing, James Miles, says the incident is likely to be a considerable embarrassment for the Chinese government.