Clean-up activities of an oil spill that affected about 25 miles (40 km) off the north shore of Long Island, New York, are expected to be complete by the end of the week, the U.S. Coast Guard said Tuesday. The spill of residual fuel oil, a heavy oil used in power generation, was discovered Friday, originating from a hole in a barge transporting 48,000 barrels of the fuel from Tosco Corp's Bayway refinery in Bayonne, New Jersey to the NRG Energy Inc.'s power plant in Montville, Connecticut, the Coast Guard said. The amount of oil spilled from the Rhode Island was not available but clean-up efforts have already reduced the affected area to about 10 miles (16 km), Petty Officer Tom Sperduto said. "We expect it to take another two or three days.