The exiled Tibetan spiritual leader, the Dalai Lama, says he will have a successor after his death, putting to rest all speculation over whether the 600-year-old institution will end with him.

“I am affirming that the institution will continue,” he said in a video message at the start of a meeting of religious leaders in the Himalayan town of Dharamshala.

He added that members of the Dalai Lama’s office would consult heads of Tibetan Buddhist traditions and other religious leaders to search and recognise a successor in accordance with past tradition.

In a message that is being seen as directed at China, he reiterated that “no-one else has any such authority to interfere in this matter”.

The Dalai Lama fled across the border to India in 1959 after a failed uprising against Chinese rule in Tibet. He set up a government-in-exile in Dharamshala and has been seen as an alternative source of power for those who resent Beijing’s tight control of Tibet.

The announcement comes at a time when the Dalai Lama is celebrating a milestone 90th birthday on Sunday. Celebrations began on Monday – the Dalai Lama’s birthday according to the Tibetan lunar calendar.

Celebrations will be attended by more than 7,000 guests, including a number of Indian ministers. Hollywood actor Richard Gere, a long-time follower, is also in attendance.

In the past, the Nobel Peace Prize-winning spiritual head of Tibetan Buddhism has been torn between whether to continue with the 600-year-old institution or not. A few years ago, he said his successor might be a girl, or that there might be no successor at all.

But in recent years, he has also said that if there is widespread support among Tibetans-in-exile for the post – which there is – then it would continue and his office would choose a successor.

He has always insisted that his successor would be born outside China, something that has angered Beijing.

Even though the Dalai Lama has always advocated a “middle way” to resolve the status of Tibet – genuine self-rule within China – Beijing regards him as a separatist. It says the standard of living of people in Tibet has greatly improved under its rule.

Youdon Aukatsang, an MP in the Tibetan parliament-in-exile, said the present Dalai Lama was a “binding and unifying force for the Tibetan movement” and some Tibetans feel somebody should be recognised soon as his successor because they worry that there may be an impact on the community and the movement going forward.

“The Dalai Lama institution is very important for the Tibetan struggle. It’s also a symbol of Tibetan identity and a beacon of our spiritual refuge. That will continue. I think there will be a vacuum, but we have to continue, we don’t have a choice,” she said.

“We have very, very big shoes to fill but we have to fill them, right? I think many people will have to get into that role, one person will not be enough.”

Experts, however, say China is also expected to name its own Dalai Lama.

“China will argue that only the Communist Party of China based in Beijing has the authority to find the reincarnation of the Dalai Lama,” Dibyesh Anand, professor of International Relations at the University of Westminster, told the BBC.

“After a period of a few months or a few years, they will have their own proteges identify a small boy as the next Dalai Lama and impose that. Of course, a majority of Tibetans are going to reject it and the majority of people in the world are going to make fun of it. But remember China has immense authority in terms of resources so they will try to impose that.”

Ms Aukatsang says that “despite all these years of trying to control the hearts and minds of Tibetan people inside Tibet”, Beijing has “completely failed”.

A Dalai Lama chosen by China, she says, “will not be recognised, not only by the Tibetans but the world will not recognise it because China doesn’t have the legitimacy to find the future Dalai Lama”.

“We are concerned but we know that irrespective of our concern, China will come up with their own Dalai Lama, we will call it the Chinese-recognised Dalai Lama. I am not worried that Dalai Lama will have any credibility in the Tibetan world or the Buddhist world.”

Tibetan Buddhists believe that their senior monks are reincarnated and a Dalai Lama is chosen by Buddhist officials if they are convinced that the one they are choosing harbours the soul of his predecessor.

The present – 14th – Dalai Lama was born on 6 July 1935 in a small Tibetan village in a farmer family and was named Lhamo Dhondub. When he was two years old, a search party of Buddhist officials recognised him as the reincarnation of the 13 previous Dalai Lamas.

According to his official biography, the clinching evidence came when the officials showed him a number of possessions that had belonged to his predecessor. The toddler correctly identified items belonging to the 13th Dalai Lama saying, “It’s mine. It’s mine”.

Enthroned before he turned four, he was educated at a Tibetan monastery and has a doctorate of Buddhist philosophy.

But in 1950, when he was 15, the troops of Mao Zedong’s newly-installed Communist government marched into Tibet. A year later, China drew up a 17-point agreement legitimising Tibet’s incorporation into China.

A Tibetan revolt in 1959, seeking an end to Chinese rule, was crushed and thousands of protesters were killed.

The Dalai Lama fled to India on foot along with 10,000 followers and settled in Dharamsala, running a government-in-exile from there. In 2011, he gave up his political role but remains Tibetan Buddhism’s top spiritual leader.

Some of those who fled alongside him still dream of going home to Tibet.

“My faith is that I will return to Tibet. If not me, my younger generations will definitely return,” said Lobsang Choedon, 84, who attended Monday’s celebrations.

Choedon’s daughter and grandchildren were all born – and have spent their entire lives – in India. Nevertheless, her 15-year-old grandson Ngawang Lhundup feels deeply connected to his ancestral homeland.

He has been listening to stories about Tibet since he was a child and says he would consider visiting Tibet even though it’s under Chinese rule.

“But if it was free from the Chinese invasion, I would be more than delighted to go back to Tibet.”