The Free Tibet group said the latest self-immolation happened outside a monastery in Ganzi in Sichuan province, about 150 km (95 miles) south of Aba, the site of eight of the last nine self-immolations since March to protest against religious controls imposed by the Chinese government.

In a statement emailed late on Tuesday, Free Tibet said it had no information about the monk's name, whereabouts, or whether he survived the incident.

Nor did it specify its sources.

Government officials, police and workers at several hotels in Ganzi, called Kandze by Tibetans, told Reuters they did not know about the reported self-immolation.

"I don't know about this, and even if I did, I couldn't be loose-lipped," said an official in the Ganzi county office.

Most people in Ganzi and neighboring Aba are ethnic Tibetan herders and farmers, and many see themselves as members of a wider Tibetan region encompassing the official Tibetan Autonomous Region and other areas across the vast highlands of China's west.

The string of self-immolations, at least five of them fatal, "represents a wider rejection of China's occupation of Tibet," said Stephanie Brigden, the director of Free Tibet, which campaigns for self-rule for the region.

The group reported "significantly increased numbers of security personnel including in Tibet's capital, Lhasa, hundreds of kilometers away from where the self-immolations have taken place."

For the Chinese government, the protests are a small but destabilizing challenge to its regional policies, which it says have lifted Tibetans out of poverty and servitude.

China has ruled what it calls the Tibet Autonomous Region since Communist troops marched in 1950. It rejects criticisms of rights groups and exiled Tibetans and has condemned the self-immolations as destructive and immoral.

"Encouraging some people to use this kind of extreme and cruel means to injure themselves is a type of violent terrorist act," China's Foreign Ministry spokeswoman Jiang Yu told a regular news briefing.

Jiang did not confirm the latest incident but said the protests were out of sync with the wishes of people in the region.

"I think a few individuals inciting a few ignorant people to violate the law and damage local social stability cannot represent the broader desires of the local people," she said.

In March 2008, protests and deadly riots against the Chinese presence spread across Tibetan regions, triggering sometimes deadly confrontations with troops and police.

Tibet's exiled spiritual leader, the Dalai Lama, who China condemns as a supporter of violent separatism for his homeland, last week led hundreds of maroon-robed monks, nuns and lay Tibetans in prayer to mourn those who have burned themselves to death or been imprisoned.

The Dalai Lama denies advocating violence and insists he wants only real autonomy for his homeland, from which he fled in 1959 after a failed uprising against Chinese rule.

But the Chinese Foreign Ministry has said the Dalai Lama should take the blame for the burnings, and repeated Beijing's line that Tibetans are free to practice their Buddhist faith.