Police have ruled out elements of sabotage in the diesel spillage which contaminated raw water in Sungai Selangor.

Inspector-General of Police Abdul Hamid Bador said today that the ongoing investigation has revealed that the incident could have been caused by negligence on the part of the company employed by the state to clean up the river.

Hamid said two of the company's employees have been detained for questioning.

"Initially, we thought that it was an act of sabotage by individual(s). Subsequently, questioning revealed certain fact that it might not be sabotage, but an act of negligence."

Hamid also said that police are looking into the possibility that a false police report was lodged in an attempt to protect company interests.