Fourteen Nobel Peace laureates urged South Africa to grant the Dalai Lama a visa Monday, after Chinese complaints apparently scuppered a trip by the Tibetan spiritual leader to the "Rainbow Nation".

The Dalai Lama was to attend a summit of Nobel peace prize winners in Cape Town next month, the first-ever meeting of its kind in Africa.

But, according to an aide, he cancelled after Pretoria denied him a visa in a bid to avoid angering China, which regards the Buddhist monk as a campaigner for Tibetan independence.

"We are deeply concerned about the damage that will be done to South Africa's international image by a refusal -- or failure -- to grant him a visa yet again," the group said in a letter to President Jacob Zuma.

Signatories include Poland's Lech Walesa, Bangladeshi entrepreneur Muhammad Yunus, Iranian lawyer Shirin Ebadi, Liberian activist Leymah Gbowee and Northern Irish peacemakers David Trimble and John Hume.

The Dalai Lama has applied three times in the last five years to visit the country once led by Nelson Mandela.

Each time the government has dragged its feet until the trip was called off.

Each prior rejection has been met with public outcry by South Africans who see it as a betrayal of the commitment to human rights embraced by their government since the end of apartheid 20 years ago.

The country's top court found in 2012 that the government had acted unlawfully by stalling on a visa application by the Tibetan until it was too late.

China -- South Africa's biggest single trading partner, with two-way trade worth $21 billion in 2012 -- regularly uses its economic and political clout to put pressure on governments around the world to limit contact with the Dalai Lama.

"We understand the sensitivities involved -- but would like to point out that His Holiness, the Dalai Lama, no longer holds any political office," the signatories said.

Instead, the insisted, he "would participate in the summit solely in his capacity as a globally respected spiritual leader."

The Nobel summit in Cape Town on October 13-15 is backed by foundations representing four South African peace laureates -- Desmond Tutu, Nelson Mandela, FW de Klerk and Albert Luthuli.

Along with the surviving South Africans -- Tutu and de Klerk -- the organisers say 13 individuals and eight organisations had confirmed that they would attend the summit, including former Soviet president Mikhail Gorbachev.

Previous summits have been held in cities including Rome, Paris, Chicago and Warsaw.

The Dalai Lama was previously barred from entry to South Africa in 2011, when he was invited to give a lecture as part of celebrations for anti-apartheid activist Tutu's 80th birthday.

At the time, Tutu described Zuma's African National Congress government as being "worse than the apartheid government".

The Dalai Lama was also denied a visa in 2009, but had visited three times before that and was personally welcomed by former president Mandela.

"The main question in diplomatic circles now is 'what did they gain?'" said David Zounmenou of the Institute for Security Studies in Pretoria.

"Under Mandela and his successor Thabo Mbeki, the questions of morality and governance were central; under Zuma we have not really seen that mention of human rights," he said.