Chinese authorities have agreed to investigate government land sales that sparked days of violent unrest in China's industrial heartland last week, a report said.

Hundreds of villagers, angered at the sale of land without their permission, attacked a police station and ransacked vehicles in the southern province of Guangdong, leaving dozens injured, local authorities and media reports said.

Officials in Lufeng city have promised to investigate the deals if locals stopped protesting, according to a report in the Southern Daily newspaper posted on the Shanwei city government website on Saturday.

Lufeng comes under the jurisdiction of Shanwei.

Unrest first broke out Wednesday in villages near Lufeng. Protests escalated after rumours of a child's death spread.

By Saturday the situation was "almost calm", the report said.

AFP calls to the Lufeng city government on Sunday went unanswered.

It was the latest in a series of protests sparked by perceived injustices in the region, known as the workshop of the world for the tens of millions of migrant workers who toil in the province's factories.

In the last reported protest in Guangdong in June, hundreds of people battled police and destroyed cars after a factory worker was wounded in a knife attack over a wage row.

In the same month, riots erupted after rumours spread that police had beaten a street hawker to death and manhandled his pregnant wife.