Crude oil from an underground pipeline operated by state-owned Petronas leaked into a river in Miri, Sarawak.

The crude oil was being transported from the off-shore West Lutong field to a terminal in the town of Miri when authorities detected the leak, Petronas said.

"The leak was spotted around 6am near the old refinery bridge along the Lutong river, about 10 kilometers from Miri," Petronas Carigali Sdn Bhd, a Petronas unit handling its gas and oil operations, said in a statement.

"An undertermined amount of crude oil had spilled into the river as a result," it said.

It said the pipeline was immediately shut down and the leakage brought under control adding: "Oil spill containment and clean-up operations are currently underway."