BEIJING: Hundreds of workers in northern China labored Saturday to contain a leak in a key oil pipeline that has left a 20-mile (33-kilometer) stretch of river polluted with diesel. An unknown amount of oil had poured from a China National Petroleum Corp. pipeline into the Wei River in Shaanxi province since a construction accident Wednesday, the state-run China News Agency said. The pipeline links the capitals of northwest Gansu province and central Henan province. A report from the official Xinhua News Agency put the amount of oil leaked at about 40,000 gallons (150 cubic meters). Chinese Vice Premier Li Keqiang told the local government to keep the spill from reaching the Yellow River, the most important river in northern China and a key symbol in China. A man answering the phone at the provincial environmental protection office told The Associated Press that people had been sent to the scene but had no details. Calls to the oil company, China's largest producer of oil and gas, were not answered Saturday. Xinhua reported that the company said the leak was under control. The China News Agency report cited Shaanxi Television as saying 20 miles (33 kilometers) along the Wei were polluted by the leak. More than 700 people were working to contain and clean up the oil-affected area, the report said.