Hundreds of emergency workers in northern China are trying to contain a pipeline leak that has spilled diesel fuel into a tributary of the Yellow River.
State media say about 150,000 litres of diesel poured into the Wei River in Shaanxi province after an accident on a state-run fuel pipeline.
The accident happened last Wednesday, but has only just come to light, the BBC reports.
Workers are said to be labouring round the clock using floating dams and solidifying agents to contain the spill.
Chinese Vice-Premier has told local government to prevent the slick from reaching the Yellow River, which is a source of drinking water for millions of people.