Protesters clashed with police who were trying to evict a 90-year-old woman to make way for a real estate project, leaving 20 people injured in a southern China town, a human rights monitor and a newspaper reported Saturday.

At one point the woman was on her roof with a homemade gasoline bomb, the Hong Kong-based Information Center for Human Rights and Democracy and the newspaper Beijing News said.

Such conflicts occur regularly in China, where local authorities are seizing farmland and older housing to clear the way for shopping malls, luxury apartments and other projects.

Violence erupted Wednesday after hundreds of police and firefighters tried to force the woman from her home in Shengzhou, in the southeastern province of Zhejiang, the reports said.

The woman, Zhang Xinghua, has been fighting eviction since 2004 and is the last holdout in the neighborhood, the Beijing News said.

About 20,000 people who gathered to protest the eviction clashed with officers, the reports said. The Information Center said 20 people were injured and six detained by police.

There was no word on whether the eviction succeeded.

An officer who answered the phone at Shengzhou police headquarters confirmed a violent incident occurred, but said he had no details.

He refused to give his name.

People evicted in such redevelopment efforts often complain they get too little compensation to buy new farmland or homes.

Zhang was offered 2,500 yuan (US$325; euro243) per square meter (US$32; euro24 per square foot) for her home, but her family wants 4,000 yuan (US$525; euro390), the Beijing News said.