Incantations ring out at Mongolia's largest monastery as worshippers pray alongside pictures of the Dalai Lama, whose 90th birthday on Sunday has raised fresh questions about the future of the 600-year-old Tibetan spiritual institution.

The statement puts to rest speculation that the Dalai Lama may be the last of Tibet's spiritual leaders, ending a line that stretches back centuries.

For much of the past century, the Dalai Lama has been the living embodiment of Tibet’s struggle for greater freedoms under Chinese Communist Party rule, sustaining the cause from exile even as an increasingly powerful Beijing has become ever more assertive in suppressing it.