The effusive support is significant, as Tibetans in exile fear China will eventually name its own rival successor to the Dalai Lama, bolstering Beijing's control over Tibet, the territory it poured troops into in 1950 and has ruled ever since.

India has hosted the Dalai Lama since he and thousands of other Tibetans fled Chinese troops who crushed an uprising in their capital Lhasa in 1959.

The Dalai Lama says only his India-based office has the right to identify his eventual successor.

"I join 1.4 billion Indians in extending our warmest wishes to His Holiness the Dalai Lama on his 90th birthday," Indian Prime Minister Narendra Modi said in a statement.

"He has been an enduring symbol of love, compassion, patience and moral discipline," he added.

"His message has inspired respect and admiration across all faiths. We pray for his continued good health and long life."

China insisted Wednesday that it would have final say on who succeeds the Tibetan spiritual leader.

India and China are intense rivals competing for influence across South Asia, but have sought to repair ties after a 2020 border clash.

US Secretary of State Marco Rubio also said in a statement that Washington was "committed to promoting respect for the human rights and fundamental freedoms of Tibetans".

"We support efforts to preserve Tibetans' distinct linguistic, cultural, and religious heritage, including their ability to freely choose and venerate religious leaders without interference," the statement added.