BEIJING - RIOTERS torched a police building and vehicles in south-west China on Saturday, in unrest triggered by allegations of a cover-up over a girl's death, according to Chinese accounts on the Internet.

The reports of the clash in Weng'an County, Guizhou province, could not be immediately verified and government and police did not answer phone calls in the early hours of Sunday.

But the accounts spreading on the Internet, despite China's state censorship, depicted a violent outburst involving thousands of people and lasting several hours.

Blogs linked to the popular Sina.com Chinese website showed pictures of thousands of people surrounding a police headquarters, riot police guarding the burning shell of the building, and burnt and overturned police vehicles.

The reports come as China seeks to quell any unrest ahead of the Beijing Olympic Games in August. President Hu Jintao has said ensuring stability is a top priority ahead of the Games.

The accounts said a youth alleged to have attacked the girl may have been the son of a senior county official or police officer.

'Without conducting a full autopsy, the police believed the girl committed suicide by jumping in a river, and they did not take mandatory measures against the suspect and ignored the family's call for a full autopsy,' said one account.

'This drew the anger of the family and public and later sparked this conflict.'

Repeated calls to the Weng'an County Public Security Bureau were not answered or did not connect, and calls to the county government were not answered after midnight on Saturday. State media carried no reports of the incident.

Some Internet reports said school students were at the forefront of the unrest in the poor, mountainous region.

Chinese websites quickly removed many messages about the incident, but others remained accessible.

'I hope that the Internet will be able to swiftly oversee the government in uncovering the truth as soon as possible and delivering justice to the family,' said one message. -- REUTERS