Twelve government officials have been sacked and three company executives have been arrested for their roles in a lake pollution scandal in Yunnan, a spokesman with the provincial supervision department said on Wednesday.

A news cameraman films at one of the sources of pollution near Yangzonghai Lake yesterday. (Photo: Xinhua)

The most senior figure involved is Chen Zhifen, vice-mayor of Yuxi, a prefecture-level city in Yunnan, who has been "ordered to resign for dereliction of duty", the spokesman said.

The other officials include Yang Zhenqiang, assistant to the mayor of Yuxi; Fang Jianhua, director of the Yuxi municipal environmental protection bureau; and Yang Xuemei, vice-director of the provincial water resources protection and monitoring station.

Disciplinary action was also taken against 14 other officials, the spokesman said.

Three executives, including the chairman, of the Yunnan Chengjiang Jinye Co Ltd, which was found to be the source of the pollutants, have been arrested for polluting the environment, he said.

At a press meeting on Tuesday, the Yuxi municipal government made a public apology for the arsenic pollution of the Yangzonghai Lake, which affected at least 260,000 residents.

"The government feels deeply sorry for the serious consequences brought about by lake pollution that affected people's lives and production," the apology letter said.

"The incident exposed our weaknesses in environmental protection as well as poor law enforcement and inadequate supervision."

The government said it would invite bids from around the world to tackle the pollution and make lake water safe again within three years.

Five million yuan (US$730,000) has been allocated to ensure the provision of safe water to residents and the ecology around the lake, a government spokesman said.

Excessive levels of arsenic were detected in the lake in June and a chemical fertilizer plant was later found to be the source.

The firm is accused of dumping untreated wastewater laced with arsenic over a period of years, which gradually contaminated the underground water.

The plant was closed down soon after the scandal broke in June.