The protestors blockaded the warehouse of Pornpop Chemical and Supply Ltd in Phra Samut Chedi district to prevent the transfer of chemicals from the compound.

Officials from the Tambon Administrative Organisation said they would file a lawsuit against the firm if it continued to operate today, while the villagers said they just want the firm out of their area.

Jampa Prachuabboon, 40, said the leak occurred on May 3 when staff were transferring concentrated hydrochloric acid from a 10,000-litre container to 20-litre containers.

The valve on the large container was broken and the acid spread like a fog over a wide area, Jampa said. She and other villagers in the area started vomiting and suffered eye and nose irritation, she said.

Some were admitted to Phra Samut Chedi Hospital while others were taken to Bangkok Hospital in Phra Pradaeng.

Jampa said she spent four days in an intensive care unit, with the firm paying the medical costs.

Local administrators and police had ordered the firm to stop operations until it repaired the valve, but it continued to smuggle hydrochloric acid and sodium hydroxide out on trucks, she said.