Tenuous calm returned Saturday to a south China town that was the scene of violent clashes between police and protestors this week, after local residents said officials had agreed to a dialogue.

Locals of Haimen township who had blocked a highway for a fourth day on Friday to protest a planned power plant expansion -- throwing bricks and getting hit by police tear gas -- said the peace could be temporary.

"It is quiet today so far, but I don't know if this will last this afternoon," a travel agent who gave only his surname, Lin, told AFP.

A highway toll gate where the clashes had flared was reopened Saturday and no protests were seen nearby, the official Xinhua news agency said.

Xinhua said that around 2,000 locals from the fishing township that is part of Shantou City in China's southern Guangdong province had gathered near the toll gate on Friday. Xinhua earlier put the number of Friday protestors at 500.

A nearby petrol station that was also the scene of clashes remained closed, Xinhua said.

Haimen residents had complained that the coal-fired power plant was behind a rise in the number of local cancer patients, environmental pollution and a drop in the local fishermen's catch, Xinhua said.

The government had said the project expansion would be suspended, but the protest turned violent and at least five people were detained by police on Wednesday for alleged vandalism, Xinhua said.

Friday's crowd dispersed at about 6:00 pm (1000 GMT) after government officials promised to release detained villagers, Xinhua said.

State-run local television on Friday night broadcast a message from Shantou Communist Party officials promising at least a temporary stop to plans to expand the plant, which is owned by state-run Huaneng Power, Lin said.

"The party secretary of the discipline and inspection committee in Shantou said on TV last night that this power plant will be stopped temporarily. He didn't say they will give up the plan. He was just trying to calm the people."

No sign of the Shantou officials' reported promise appeared on the local government website and a government duty officer reached by telephone said he did not know about the dialogue or any agreement with local residents.

Friday television footage from broadcaster Cable TV in nearby Hong Kong showed riot police firing gas cannisters from the toll gate towards a crowd of residents gathered on the highway.

Some residents told AFP that a 15-year-old boy and a middle-aged woman had been killed in violence on Tuesday, but a local official quoted by Xinhua denied any deaths.

The latest protests in Guangdong, China's wealthiest province and its manufacturing heartland, follow months of labour unrest as the country's export growth slows, forcing factory owners to cut pay and reduce staff.

A protest in the nearby village of Wukan attracted worldwide media attention.

Wukan villagers ended their long stand-off with authorities on Tuesday after a senior provincial official pledged to free three detained protest leaders and investigate their grievances.