A new spill has occurred in Alaska's Prudhoe Bay oil field.

The Department of Environmental Conservation says the spill was discovered Monday by a BP oil field operator doing a routine inspection.

State officials announced the spill Tuesday morning. They say the spill was at a drill site and was coming from a 6-inch pipeline carrying a mixture of oil, water and natural gas.

The cause and amount of the spill are not known at this time.

BP operates the Prudhoe Bay oil field — North America's largest oil field.

Last month, one of the North Slope's biggest spills of 46,000 gallons of oil, water and natural gas was reported at another BP-operated oil field. That spill occurred when an 18-inch line split.