CALGARY, Alberta - The Alberta Energy Regulator is investigating a leak on a NuVista Energy pipeline in northern Alberta which spilled 100 cubic metres, roughly 629 barrels, of oil and water emulsion, the regulator said on Wednesday. The leak on the pipeline, 50 kilometres (31 miles) northeast of Rainbow Lake, was first identified during an aerial surveillance flight on Friday, and covered an area approximately 70 by 100 metres. There was no impact on wildlife reported. Bob Curran, director of public affairs at the Alberta Energy Regulator, said NuVista shut in the line and a clean up was under way. AER staff are on site investigating the spill. NuVista was not immediately available for comment. Last month an oil sands pipeline owned by CNOOC subsidiary Nexen Energy leaked 31,500 barrels of bitumen emulsion in northern Alberta, drawing fierce criticism from environmentalists.