Video footage has come to light that shows a deep rift at the heart of Tibetan Buddhism, and rivalry that challenges the status of the Dalai Lama.

Just one month ago, the Tibetan teenager who is also the Karmapa, the most revered lama after the Dalai Lama, gave his first press conference after his escape from Tibet in December 1999.

It was an elaborately managed affair, worthy of any spin-conscious political party. The Tibetan government-in-exile, in Dharamsala, northern India, wanted to protect Urgyen Trinley Dorje, 17th Gyalwa Karmapa, from awkward questions.

The Karmapa's supporters portrayed the media event as an opportunity for the Karmapa to explain the reasons behind his escape, but it was equally about raising his profile ­ and with very good reason. For there is a rival Karmapa with whom Urgyen Trinley Dorje's entourage have an increasingly bitter relationship.

Two years after Urgyen Trinley Dorje's 1992 enthronement in Tibet (with very public Chinese support), the rival, Tai Trinley Dorje, underwent a virtually identical ceremony at a Buddhist centre in Delhi. The ceremony became violent when monks supporting opposite sides began stoning each other.

The incident was confirmed with the discovery that an Indian journalist, Vijay Kranti, had captured the troubles on videotape. This footage has not been publicly seen until now. It shows rival monks throwing stones at each other and the injuries they caused.

Kranti, who has travelled extensively with the Dalai Lama, places this dispute within a wider context. He argues that the Tibetans' reliance on reincarnation for choosing new leaders is flawed and that it is time for them to reassess it.

He makes some powerful arguments ­ not least about the Tibetans and China. "When they are fighting with China they cannot afford to have leaders whose identity or genuineness is challengeable," he says, adding, "when this Dalai Lama passes away, China can put up a new baby saying, 'Here is the real Dalai Lama.' What will the Tibetans do then?"

The rival Karmapa's spokesman, Karma Wangchuk, claims Situ Rinpoche, one of four senior lamas who appointed Urgyen Trinley Dorje, virtually colluded with the Chinese over the selection. He also claims the Dalai Lama is really only in charge of his Gelugpa Buddhist sect and so is the political, not spiritual, leader of the Tibetan nation.

Situ Rinpoche has also had to face allegations that the "prediction letter" from the 16th Karmapa he produced after that Karmapa's death was not genuine. He evades questions about the letter's authenticity by maintaining it is "unimaginable that His Holiness [the previous, 16th Karmapa] will forge a letter". He thus sidesteps the accusation that it was not the previous Karmapa who carried out the forging, but himself.

Meanwhile Urgyen Trinley Dorje is still a resident at Gyoto Monastery outside Dharamsala. Guarded by the Indian police and his followers he is, in effect, still a prisoner. He has been given refugee status but his movements are restricted. He cannot go to his traditional seat at Rumtek Monastery, in the isolated state of Sikkim, and collect the symbolic Black Hat that would crown him as the Karmapa. His rival has more freedom to travel, although Rumtek appears similarly out of bounds.

The losers in this inter-sect rivalry are ordinary Tibetans ­ exiled or in the country. They are no nearer reclaiming their homeland than when the Dalai Lama fled in 1959 with 90,000 of his followers. Urgyen Trinley Dorje may yet discover that escaping from Tibet was the start, not the end, of his problems.