PETALING JAYA (THE STAR/ASIA NEWS NETWORK) - Water supply was disrupted on Tuesday (Nov 10) to more than 1 million people in Kuala Lumpur and Selangor districts after four water treatment plants were shut down due to suspected contamination in a major river in Selangor state.

Water supply company Pengurusan Air Selangor said water supply was shut from 6pm on Tuesday, affecting 1,139,008 consumer accounts.

Air Selangor earlier on Tuesday ordered the shutdown of the Phase 1,2, 3 and Rantau Panjang treatment plants as pollution was detected.

The water contamination at Sungai Selangor - a major river that supplies water to the plants - was detected at 12.45pm on Tuesday, Air Selangor said in a statement.

The stop-work order is expected to affect water supply in 1,279 areas in Kuala Lumpur, Petaling, Klang, Shah Alam, Kuala Selangor, Hulu Selangor, Gombak and Kuala Langat, the company said.

The source of the latest case of pollution allegedly originated from a plant operated by national wastewater treatment firm Indah Water Konsortium, said Selangor executive councillor Hee Loy Sian as reported by Malay Mail online news.

But Indah Water's CEO Narendran Maniam said the company had halted effluent releases since Nov 4, and claimed it was caused by third party illegal waste dumping instead.

Mr Narendran said the company had informed the relevant authorities about the pollution and had carried out treatment to neutralise it.

"We have lodged a police report about this matter and it is now being investigated by the authorities as to ascertain the actual cause of the pollution," he said as quoted by Free Malaysia Today news site.

The Klang Valley, as KL, Putrajaya and Selangor districts are often referred to, has been hit by a series of water supply disruptions in the last three months, causing deep public anger.