BEIJING Up to 100,000 farmers clashed with the police in southwest China, protesting compensation payments for farmland requisitioned to make way for a hydroelectric plant, local residents and news media reports said Monday. Unrest at the Pubugou hydroelectric project on the Dadu River in Sichuan Province began last Thursday and peaked Friday when locals marched on the Hanyuan County government offices carrying the corpse of a dead protester, Hong Kong's Sun Daily said. Several people reportedly were killed and scores injured in the clashes, as some 10,000 People's Armed Police descended on the area to maintain order, the newspaper said. It was the second episode of widespread civil unrest reported in the last two days. In Henan, the authorities declared martial law in part of the province after clashes between minority Hui Muslims and ethnic Han Chinese, residents and officials said Monday. The fighting there flared Friday and continued into the weekend after a Hui taxi driver's car hit and killed a 6-year-old Han girl, prompting recriminations between different ethnic groups in neighboring villages, residents said. A person briefed on the incident by the police said that 148 people had been killed, including 18 police officers sent to quell the violence. The Chinese media have reported nothing about unrest in Henan. But a news blackout would not be unusual, as propaganda officials routinely suppress information about ethnic tensions. Though most Chinese belong to the dominant Hans, the country has 55 other ethnic groups, including several Muslim minorities and others with ties to Tibet, Southeast Asia, Korea and Mongolia. Hui Muslims, scattered in several provinces in the central and western parts of the country, are relatively well integrated into Chinese society and not generally considered a threat to stability. Outbreaks of Hui unrest were not uncommon in the 1980s, and tensions continue to bubble to the surface after even minor provocations. Many Hui areas remain impoverished despite rapid economic growth in China's urban and coastal regions, and some members of minority groups say the Han-dominated government does little to steer prosperity to them. The traffic accident last Friday set off large-scale fighting after relatives, friends and fellow villagers of the girl who was killed, most of them Han, traveled to the mostly Hui village of the taxi driver to demand compensation. The rival villagers failed to settle their dispute, which quickly grew to involve thousands of people in Zhongmou County between the cities of Zhengzhou and Kaifeng, according to two accounts of the incident. The local police failed to contain the unrest and the authorities deployed the paramilitary People's Armed Police to restore order. Martial law was declared over the weekend, people in the area said, adding that the situation had since stabilized. A person briefed on the clashes said the authorities may have been particularly alarmed after the police stopped a 17-truck convoy carrying Hui men to the area from other counties and provinces as it passed through Qi County, near Zhongmou. Blockades were set up on major roads in the area, and some bus services were halted. It suggests that word of the violence may have spread through a network of Hui and perhaps other Muslim groups, and that mutual support among them is relatively strong. But details were sketchy and difficult to confirm. China's countryside and second-tier cities are rife with unrest among peasants and workers complaining about corruption, unpaid wages and other issues. Violent protests, once extremely rare, occur frequently. Last week, rioters set fire to police cars and looted government offices in Wanzhou, in Chongqing municipality in southwest China, after an argument between several people set off a riot involving as many as 10,000 people, residents and Western news agencies reported. The Sichuan demonstrations succeeded in stopping the project, which was scheduled to dam the river on Thursday. Marchers also ransacked government offices in Hanyuan County, it added. "It happened on the 29th. It began during the day and lasted until eight or nine in the evening," said a man at the Hanyuan County government who identified himself as Liu. "There were many, many people involved, I don't know exactly how many." The paper said 100,000 farmers were involved, although an official at Dashu township said there were only 20,000 protesters and that by Monday construction on the dam project had resumed. The lands of some 100,000 farmers in 40 townships that are spread throughout three counties are expected to be submerged by the dam project, an official said. The Dadu River is a tributary of the Min River, which eventually flows into the Yangtze, China's longest.