BEIJING — Thousands of farmers in southwest China rioted at a government office after authorities imposed heavy fines on families that had more children than allowed under the country’s family planning policy, a newspaper and a villager said yesterday.

Anti-riot police were called in after villagers set fires and smashed cars Saturday at the Shabi township government office in the Guangxi region, Hong Kong ‘s Ming Pao Daily News said.

One person was injured as villagers and government officials hurled stones at each other, the newspaper reported. Demonstrators also knocked down a wall and damaged offices, it said.

Lu Wenhua, 23, a town resident, said protesters were angry because the government had levied fines of more than $1,300 on families that had too many children. “The fine is too heavy because the annual income of the villagers was only 1,000 yuan [about $130]. It is too much for people to bear,” he said in a telephone interview.

China’s family planning policy — implemented in the late 1970s — limits most urban couples to one child and families in some rural areas to two in an attempt to control population growth and conserve natural resources.

Ming Pao said all public servants had been ordered to collect $65 from people who violated the family planning policy. If violators failed to pay within three days, their homes would be demolished and their belongings seized.

The protest is the latest in a growing number of violent incidents across China in recent years as ordinary Chinese vent anger over official corruption, a growing rich-poor gap, and land confiscations.