From correspondents in Beijing, China, 06:33 PM IST

Riot police have quelled two violent protests by thousands of people in southern and eastern China, in the latest of several recent clashes between ordinary residents and local authorities, officials and a rights group said Friday.

Up to 30 people were detained for questioning after riot police broke up a protest by migrant workers demanding compensation for a teenage boy who was seriously injured after he climbed into a textile factory in the eastern city of Ningbo, police said.

'There are now 20 to 30 under investigation and being interviewed,' a police officer in Ningbo's Xiangshan county told DPA by telephone.

The officer said 'mass rioting' broke out after factory workers seized the 14-year-old boy as a suspected thief and called police, apparently resulting in the boy jumping from a building as the police arrived.

'The reason why he jumped is still under investigation,' he said.

The Xiangshan police officer said the boy was treated by a local hospital for serious injuries but was out of danger.

He said no police were injured in the clash with protestors, but the Hong Kong-based Information Centre for Human Rights and Democracy said 20 others were injured.

The Information Centre said some 500 migrant workers gathered outside the factory Thursday, and thousands of onlookers swelled the crowd to about 10,000 before the riot police arrived.

It said another 50 people were injured and 20 detained after riot police clashed with thousands of protestors angered by an illegal fund-raising scheme in the southern province of Hunan Wednesday and Thursday.

In one of the most serious incidents, up to 30,000 people rioted after the mystery death of a teenage girl in the south-western province of Guizhou in late June.

The government later said a string of unresolved 'social grievances' and encouragement by criminal gangs had sparked the rioting.

(Staff Writer, © IANS)