An oil spill in Alaska's North Slope reportedly went undetected for days and was only discovered after an oilfield worker smelled the petroleum.The crude oil leaked from a corrosion hole in the pipeline approximately one-quarter inch in diameter for at least five days. The pipelines leak-detection system did not report the spill. BP Exploration Alaska, a subsidiary of BP has been recently criticized by industry watchdogs for cutting maintenance operations. It is believed in excess of 200,000 gallons of crude oil leaked from the 34-inch diameter pipeline, making it the largest spill ever in the North Slope. The spill was contained to approximately a two-acre area. At this point, about 50,000 gallons of crude has been recovered. However, harsh cold has hampered the recovery effort. Last night temperatures dipped to 70 degrees below zero.