China on Wednesday confirmed police shot dead a "rioter" in a Tibetan-inhabited area, saying they had to use lethal force after a violent mob attacked them, state media said.

China's Sichuan province, which has big populations of ethnic Tibetans, many of whom complain of severe repression, has been rocked by violent clashes this week -- some of the worst since huge protests against Chinese rule in 2008.

Citing local authorities, the Xinhua news agency said the "rioters" in Sichuan's Seda county -- where rights groups say two Tibetans were killed in a protest -- fired at police during the attack on Tuesday, injuring 14 officers.

"Police were forced to use force after efforts involving persuasion and non-lethal weapon defence failed to disperse the mob," the report said.

Local authorities quoted by Xinhua said one "rioter" was killed and another injured. Police also arrested 13 people for their role in the violence.

The Chinese government has also blamed another deadly clash in nearby Luhuo on Monday on violent protesters, but Free Tibet, which has contacts in the area, said the demonstration there was peaceful until police opened fire.

"It was only at this point that Tibetans responded by throwing stones at the municipal building, some of which broke windows," the London-based advocacy group said.