The Dalai Lama's request for a visa to attend Desmond Tutu's 80th birthday has left South Africa to decide whether to insult the beloved anti-apartheid hero or alienate its top trading partner.

One week before Tutu's October 7 birthday, the government has refused to say if the exiled Tibetan spiritual leader can visit, after it denied him a visa in 2009 -- and openly admitted its fears of angering Beijing.

"The desire of Pretoria not to antagonise China is pretty consistent," said Matthew McDonald of the Centre for Chinese Studies.

"They are one of our most important economic partners, and other countries in Europe and Africa have faced economic consequences if seen to be interfering in their domestic agenda."

China is South Africa's biggest trade partner with exports from Africa's biggest economy reaching $4.9 billion (3.7 billion euros) in the first six months of the year.

Since barring the Dalai Lama two years ago, South Africa has inked a major trade pact with the Asian giant and joined the emerging economies BRICS group that also includes Brazil, Russia and India.

"It is surprising that the South African government still feels that there is something to lose from souring our Chinese relations. One would have thought that the relationship has become more equal," said McDonald.

"The fact is that all this indecision makes us look bad -- and that need not be the case if the issue were handled a little less clumsily by officials in Pretoria."

The controversy over Beijing's influence comes as Deputy President Kgalema Motlanthe on Friday wrapped up a four-day visit to China, where he cinched investment and trade deals and met President Hu Jintao.

The Chinese foreign ministry would not be drawn on the visa application but praised South Africa for its support on Tibet, which the Dalai Lama fled in 1959.

"China highly appreciates South Africa's valuable support to China on the issues of Taiwan and Tibet and related issues," foreign ministry spokesman Hong Lei told journalists.

South Africa has denied being pressured by China but also dodged questions on the visa, even though Tutu has sharply criticised the government, which he said seemed to "want to kowtow to a hugely repressive regime".

Tutu has invited the Dalai Lama, a fellow Nobel Peace Prize winner, to deliver an inaugural peace lecture on October 8.

University of Pretoria political lecturer Roland Henwood says that defying the world's second-biggest economy is unlikely to end relations.

"The bottom line is, what will China do if South Africa allows the Dalai Lama in?" he said.

"Will they sever ties, will they stop investing? I don't think so. The Chinese are way too pragmatic to do that. Maybe the South African government is too sensitive and allowed itself to be put in a position where they shouldn't be."

President Jacob Zuma's government plays a key role in Africa's international presence with a non-permanent seat on the UN Security Council.

But it has been criticised for flip-flopping on issues and for stepping away from its human rights principles that led to the fall of apartheid under Nelson Mandela, who welcomed the Dalai Lama to South Africa during his presidency.

"Principle is important in informing foreign policy, but to the same extent governments must be open to the realities and have a pragmatic approach to some issues," said Henwood.

"This is clearly an issue where pragmatism and principle must be aligned and must be solved," he said. "There are going to be similar issues in the future that, if not dealt with properly, will show a lack of an even-handed approach or lack of a principled approach."

Zuma's government had to act decisively, he said.

"This is something where leadership is required, someone must take a decision, explain the decision and live with the consequences."