When meditation master Thich Nhat Hanh takes a wheelchair tour of the forested pagoda in Vietnam where he has come to die, the 92-year-old is greeted by crowds of devotees -- and secret police assigned to watch him.

The monk-turned-peace-activist credited with bringing mindfulness to the West, from the homes of Hollywood celebrities to Silicon Valley boardrooms, spent nearly four decades in exile.

In that time he set up retreats around the world and wrote over 100 books including on mindfulness and meditation -- a cornerstone of a $4.2 trillion dollar global wellness industry espoused by Oprah Winfrey, Arianna Huffington and tech billionaire Marc Benioff.

Initially, the slight monk with a serene smile was banished for calling for an end to the Vietnam War.

But the Zen master, whose reach within Buddhism is seen as second only to the Dalai Lama, was kept away as he advocated religious freedom around the world including in the communist country where all faiths are strictly controlled.

Vietnamese Buddhist monk Thich Nhat Hanh is living out his last days at the scenic Tu Hieu pagoda / © AFP

He has been permitted to see out his final days at his Tu Hieu pagoda in the ancient city of Hue, Vietnam's Buddhist heartland.

But even in the twilight of his life, Thich Nhat Hanh -- unable to fully speak or walk since a 2014 stroke -- is closely monitored by plainclothes police who keep vigil outside his gated compound.

"It's not a completely free country, everything is subject to observation and the government always wants to have everything under their control," said one of his longtime attendants, requesting anonymity.

- Tears of joy -

Authorities in the Buddhist majority one-party state are wary of organised religion and last year passed a law requiring faiths to register and report all activities.

The government is particularly uneasy about leaders like Thich Nhat Hanh, who counts hundreds of thousands of followers at home and abroad -- including Oprah who keeps one of his books by her bedside.

Business titans like Salesforce CEO Benioff have embraced his mindfulness philosophy to boost innovation and improve bottom lines.

Since his return to Vietnam last month, hundreds have flocked to his pagoda to join the monk on his outings around the temple's lush gardens.

Since the Zen master's return to Vietnam, hundreds have flocked to his pagoda in the Buddhist heartland of Hue / © AFP

Most are devoted to his spiritual messages, not his politics.

"He taught us to love people, to love ourselves, to love nature," said Tran Thi My Thanh, who made the pilgrimage with friends from Ho Chi Minh City.

"We were so moved that we burst into tears, I couldn't control myself," she said after walking with Thich Nhat Hanh, who was wrapped in brown robes and pushed in his wheelchair by attendants.

Since Thich Nhat Hanh was allowed back into the country in 2005, the first of a handful of controlled visits, he has called for greater religious tolerance.

His messages have not always been welcomed: in 2009 his followers were driven from their temple in southern Lam Dong province by hired mobs.

"(The government) fears any organised group that has a mass following, just like how the Chinese government treated Falun Gong," said Tuong Vu, Asian Studies director at the University of Oregon.

- No more fighting -

Religious leaders in Vietnam have proven their capacity to mobilise the masses.

Catholic priests have led environmental protests, Hoa Hao Buddhists have waged anti-communist demonstrations, and Protestant Montagnards have clashed with authorities over land rights in the central highlands.

But Thich Nhat Hanh's disciples say they come in peace.

"We know that Vietnam has difficulty, and we know the world also tries to help Vietnam open up, to have more freedom, more democracy... we try to help also, but we do it in a Buddhist way," said Thich Chan Phap An, one of Thich Nhat Hanh's closest disciples.

The famous monk's aide, sister Dinh Nghiem, says that after a lifetime of pushing for peace he is just 'enjoying his time' / © AFP

"It's not wise to have confrontation, but it's very good to have communication," he told AFP.

It's a message that Thich Nhat Hanh harnessed in 1966 on a trip to the US where he met Martin Luther King Jr, who joined his calls to end the war and later nominated him for a Nobel Peace Prize.

Thich Nhat Hanh was barred from returning home, his anti-war stance deemed traitorous by both north and south Vietnam, and spent the next 39 years in exile in France.

His disciples say he is overjoyed to be back in his ancestral homeland, and after a lifetime of pushing for peace he can finally relax.

"No more fighting, he is just enjoying his time," said close aide, Sister Dinh Nghiem.