HANOI (Reuters) - Vietnam’s ruling Communist Party Secretariat said on Friday it was punishing four high-ranking government officials over the so-called Formosa incident, the government said in a statement on Facebook.

The Secretariat has rebuked Nguyen Minh Quang, the former environmental minister of Ha Tinh province, and dismissed his two deputies and the former party chief secretary of the province, Vo Kim Cu. The statement did not say when the punishment would take effect.

The Formosa incident occurred a year ago at a steel mill being developed by Taiwan’s Formosa Plastics Corp. An accidental release of chemicals, including cyanide, phenols and iron hydroxide, eventually polluted more than 200 km (125 miles) of the Vietnamese coast.

More than 50 violations at Formosa’s steel mill, including the unauthorized use of a dirtier production process, led to the disaster. It sparked several public protests, with coordinated rallies in major cities and an outpouring of anger on social media.

The officials were “irresponsible and loosened their management and supervision on environment safety, leading to serious damage to the environment and local people,” the statement said.

Those punished were among 11 government, provincial and industry officials who were named in February, 11 months after the disaster. Formosa agreed last June to pay $500 million in compensation.

The environment ministry has said it will probably take a decade for the affected region to completely recover from the accident.