Inspector-General of Police Abdul Hamid Bador has pledged to use the full force of the law against those who sabotaged the water supply in Selangor by spilling diesel into the river.

The police may detain the perpetrators under the Security Offences (Special Measures) Act 2012, Hamid said in Kuala Lumpur today.

"Sabotaging the essential utility (is a serious offence), where one could (before) be detained under (the defunct) Internal Security Act 1960. This shows how important the matter is.

"Anyone who sabotages the essential utility can be detained under Sosma and charged with the toughest law," he said.

"Four million people have been affected and I will not hesitate to act. I have instructed Selangor police chief (Noor Azam Jamaludin) to go on the ground (to probe the water sabotage)," he said.

On July 22, the National Water Services Commission (Span) lodged a police report on two incidents of pollution of the raw water source in Sungai Selangor.

Four water treatment plants had to shut down on July 19 and July 22 respectively, causing the closure of Phases 1, 2 and 3 of the Sungai Selangor Water Treatment Plant and the Rantau Panjang Water Treatment Plant.

Yesterday, Water, Land and Natural Resources Minister Xavier Jeyakumar said the police identified elements of sabotage behind the diesel spillage which contaminated raw water in Sungai Selangor.