A protest staged by thousands of rural workers in central China ended in violent clashes last week, reports say.
Several people were injured as up to 20,000 people clashed with 1,000 police in Hunan province on Friday, a local official told Reuters news agency.
The Boxun Chinese news website said the clash was sparked by rising public transport costs. A witness told the BBC sporadic incidents continued on Monday.
Rural regions of China have seen mounting unrest in recent years.
Thousands of protests were held last year amid growing discontent over the widening gap between rich and poor and corruption among officials at local level and above.
The latest reported unrest came as the Chinese legislature, the National People's Congress, held its annual session in Beijing.
At least nine police cars were burnt during the clashes, the Boxun report said.
Zhan Zilin, an eyewitness and a local activist, told the BBC Chinese Service that "the authorities sent over about 1,000 armed police, special police and local police and attempted to cordon off the roads in front of the local police station and government buildings".
He said the police were confronted by protesters and "large-scale conflicts broke out".
The Reuters news agency reported that police were armed with guns and electric cattle prods.
A number of police and protesters were injured - with some taken to hospital - but none were thought to be in a serious condition.
The official, from the Hunan city of Yongzhou, told Reuters that the protesters "were not satisfied with some government behaviour".
"They were also unhappy about official corruption," the official added.
The overseas-based Boxun, which is blocked inside China by the Beijing government, reported that protesters had been dissatisfied with the rising cost of bus prices.
Mr Zhan said that sporadic incidents were still going on on Monday.
"This afternoon, several dozens of people were injured, including some passers-by; four police vehicles were burned," he said.
The Chinese government has introduced a series of measures to try to address the sources of discontent in rural communities.
They include pumping billions of dollars into the rural economy in the form of farm subsidies, as well as reining in the seizures of farmland for development and tackling government corruption.
The more the Chinese people give grief to the bastards running the show, for whatever reasons, the happier I feel. We can only hope they are too stupid to pull a Hungary and engage in genuine reform, right up until the moment the regime topples.