Several local officials and residents confirmed there had been a protest Friday in Tonghua, but details of the report by the Information Center for Human Rights and Democracy, including the size of the protest and the manager's death, couldn't be confirmed.

The report said workers from Tonghua Iron & Steel Group in Jilin province blocked roads and destroyed several police cars in the protest, which it said left more than 100 people injured.

The rights group said some of the protesters beat to death a man named Chen Guojun, who it said was the general manager of Beijing-based Jianlong Group, citing local police and a friend of the executive. Mr. Chen was working at Tonghua Iron & Steel as part of his company's takeover plan, the report said.

The rights group said as many as 30,000 people took part in the protest, which would make it large even by the standards of China, where sizable protests happen frequently.

Officials at Tonghua Iron & Steel couldn't be reached for comment. A person who answered the phone at Jianlong's Beijing headquarters Sunday said that he knew nothing about the protests and that other company representatives were unavailable.

After the protest, on Friday evening, Tonghua Iron & Steel issued a notice on local television informing its employees and their families that the provincial government had decided to ask Jianlong to shelve its acquisition plans and withdraw from further involvement in Tonghua's restructuring.

The protest could put a crimp in Beijing's efforts to consolidate the Chinese steel industry, the world's largest by output.

The central government wants to eliminate surplus production capacity and create larger, globally competitive players in the industry, which like many industrial sectors in China -- including automobile manufacturing -- is dominated by local governments that have long resisted consolidation efforts.

The protest also illustrates the challenge for China's Communist Party rulers from unrest by workers and others who have few effective legal means for addressing their grievances in the authoritarian country. On Saturday, two local officials, including a municipal party chief, were removed from their posts in the Hubei province city of Shishou for "mishandling" a large protest that occurred there last month, the state-run Xinhua news agency reported. That incident, triggered by public suspicions of corruption in the death of a young restaurant chef, involved hundreds of people.

The takeover of Tonghua Iron & Steel, the company involved in Friday's incident, has been years in the making. In 2005, Jianlong took a 36% stake in Tonghua for an undisclosed amount as part of a restructuring of the provincial-government-owned company, according to the local government. A downturn in the steel industry that started last year triggered losses at Tonghua, and Jianlong sought to withdraw its investment. Steel prices rebounded earlier this year, helped by China's massive economic stimulus plan, and Tonghua Iron & Steel posted a 43 million yuan ($6.3 million) profit in June. Jianlong then reversed course and bid to become the majority shareholder.

The Information Center for Human Rights and Democracy said Tonghua's workers feared job losses and limited severance payouts in a merger with Jianlong. The protesters also complained they hadn't been consulted about the plan before it was announced.

The information center in the past has been the first to report incidents of unrest in China, which the government is often slow to acknowledge. The center was founded in 1993 by Lu Siqing, a mainland Chinese dissident who fled to Hong Kong that year. Mr. Lu says he collects and verifies reports of human-rights violations and protests from informants across the country.

A representative of the community management office in a Tonghua neighborhood where many steel workers live said Friday's protests had been "a really big thing, and most of the residents know about it."

A government official in Erdaojiang district, where Tonghua Iron & Steel is located, referred questions to other departments, where calls went unanswered. A woman at the same office told the Associated Press that a protest had occurred Friday but said she had no details of deaths or arrests. Local police declined to comment.

Many blog posts of the incident on Chinese Web sites were removed as of Sunday, apparently by censors. Chinese Workers' Research, a Web site covering Chinese labor issues, posted what it said was a detailed account of the protests written by an employee of Tonghua Iron & Steel.