State executive councillor Ling Tian Soon said the chemicals were found at about 3.15pm after complaints about a strong chemical odour.

“The chemical smell was detected in the area during the inspection around noon, prompting authorities to continue searching along the river until they found the suspicious chemicals,” he said in a Facebook post today.

He noted that there was an oil spill on the river’s surface, and samples were taken while part of the spill was cleared.

The authorities are awaiting the test results of the chemicals, he said.

Ling said the state government and authorities strongly condemned the illegal disposal of chemical waste. He urged those with information on the incident to contact the environment department.

On Tuesday, a foul odour was reported in Taman Daya, Taman Mount Austin, Taman Istimewa, and Kampung Melayu Pandan. Environment officials detected ammonia gas levels exceeding normal thresholds in the Sungai Pandan area in Kampung Melayu Pandan.

Unidentified packages were also discovered dumped along the banks of the Sungai Pandan tributary near Taman Daya two days ago.