The Dalai Lama's special envoy has said that Chinese pressure on South Africa to bar the exiled Tibetan spiritual leader from attending a peace conference has humiliated the African country.

"A nation that wants to be a global power; this is how you react?" Lodi Gyari said on at the Heritage Foundation think tank, referring to China.

China, he said, had embarrassed its largest African trading partner by acting "with total disregard" for how the world would see South Africa's decision to deny the Dalai Lama a visa.

Gyari, in often deeply pessimistic remarks, also said China's recent crackdown in Tibet is pushing angry Tibetans away from the Dalai Lama's peaceful efforts to establish meaningful Tibetan autonomy within China.

Even the usually optimistic Dalai Lama has begun questioning his attempts to engage China, Gyari said, though he has not given up.

He warned that without the Dalai Lama, who is 73 and increasingly frail, "the Chinese will have no one who can help find a solution on Tibet".