Employees of a Huizhou logistics company who are suspected of pouring tons of industrial oil into a Shenzhen reservoir have been arrested, officials with the Shenzhen Municipal Public Security Bureau said yesterday.

The suspects were arrested during a special operation Sunday afternoon in Longgang District. The police refused to reveal how many people were involved in the case.

The affected Chi'ao reservoir in Longgang District supplies water to more than 300,000 local residents living in the Pingshan and Kengzi areas in the district.

A spokesman for the Longgang water resources bureau, who refused to be named, said the contamination had been "effectively controlled," although the incident had affected water supply to nearby residents for a short period of time.

The reservoir was heavily polluted after the suspects poured some 30 tons of heavy oil into it Thursday night.

The spill was discovered by an employee of the Pingshan water supply company who inspected the reservoir Thursday night. Witnesses said they saw a layer of filthy black oil extending between 300 and 500 square meters.

The district's water resources bureau sealed off the reservoir Thursday night, and required water supply companies in nearby areas to process and then discharge all polluted water. The reservoir's water quality met the health authorities' standard yesterday, after all the oil had been removed.

(Shenzhen Daily September 12, 2007)