BANGKOK (AP) -- Protesters demanding farmer subsidies to offset losses from falling world rubber prices clashed with police in southern Thailand, throwing bricks and acid-containing bottles at the officers, authorities said.
Twenty police officers and four rescue volunteers were injured in the clash Thursday evening as protesters blocked a main road in Bang Saphan district in Prachuap Khirikhan province, Deputy Prime Minister Pracha Promnok said Friday.
He said one of the officers had a concussion and was being treated in intensive care.
Video footage from television channel ThaiPBS showed masked protesters throwing glass bottles and shooting slingshots at police early Friday morning on a main road in Bang Saphan, which is 366 kilometers (227 miles) south of Bangkok.
It also showed two cars were set on fire near the protest site.
Pracha said the protesters burned two cars belonging to a newspaper and a television news crew and another police car, prompting the police force to use tear gas to control the crowd.
In a telephone interview with The Associated Press, Songklod Cheunchoopol, an anti-government ex-soldier who joined the protest on Thursday, accused the police of shooting giant firecrackers that caused the villagers to panic and started responding the police. He said the police used tear gas against the demonstrators but did not fire any gunshots.
The confrontation was fueled by tension that began Thursday evening between the young protesters and the police force in Prachuap Khirikhan province.
Police Col. Narong Supa-aim said on Thursday that about 50 mostly young protesters out of a group of about 250 blocking the road attacked his men by hurling bottles of an acidic liquid and bricks at them. He said 10 police including the provincial police chief were slightly injured in the first round of the clash, and 10 protest leaders were detained but not charged.
Thailand's government established a Cabinet-level team to negotiate with the protest leaders, with an initial meeting scheduled for Friday.
There were also scattered scuffles at bigger protest sites in Surat Thani and Nakhon Si Thammarat provinces. But tensions seemed to have eased from the previous few days as the government indicated more willingness to negotiate.
There had been fears that the protesters would try to block provincial airports, some of which serve key tourist destinations. Rail services have resumed after protesters earlier blocked train tracks.
The government has offered to subsidize the farmers with cash payments pegged to the size of their plantations, while the farmers are demanding that they be paid a guaranteed price for their product. The government already maintains an expensive subsidy program for rice farmers.
Thailand is the world's top producer and exporter of natural rubber, which is used in products from condoms to car tires.