A woman blew herself up on Thursday to protest the demolition of her house in southwest China, killing two people and injuring 14, the official Xinhua news agency said.

The woman, who also died on the spot, was at a local government office in Yunnan province negotiating compensation for the loss of her home when she detonated explosives attached to her body, Xinhua said.

"We have opened an investigation. I can't tell you anything, but three people were killed and 14 were injured," said an official reached by telephone at the local government office, who refused to give his name.

"Of those (injured), four were badly hurt and are now on their way to hospital in Kunming," he added, referring to the capital of Yunnan.

A witness told Xinhua the woman blew herself up after she was asked to sign documents relating to compensation, and was killed immediately.

No further details about the dispute were immediately available, but government land grabs and forced relocations frequently trigger violent protests in China by desperate citizens who feel their rights are being trampled.

Last year, a suicide bomb attack by a jobless man angry over a land dispute left two civilians dead in the eastern city of Fuzhou.

Qian Mingqi, who was 52, lost his home in 1995 to make way for a highway, and then had a second home demolished in 2001 to make way for the same highway, according to reports published at the time.

"For the past 10 years, I have suffered a great injustice. I cannot find justice. I was forced to go down a road I didn't want to take," the bomber wrote on his microblog account.

"I will get justice myself, through concrete action."

Also last year, more than 40 people were injured when a disgruntled former employee set off a petrol bomb at a bank in the northwestern province of Gansu, in protest over being laid off.

And in September 2010, three people set themselves on fire in Fuzhou over a land dispute. One died.

Wronged Chinese queue up in Beijing or provincial capitals to petition authorities over injustices, but many complain of official unresponsiveness to their concerns.