British Petroleum PLC, announced late Sunday that it would shut off its biggest U.S. oil field due to corrosive oil pipes.

The London-based company had begun to shutdown the Prudhoe Bay oil field located in Alaska after discovering a severe corrosive in one of the pipes. The company said Sunday had contained a small spill estimated to be 4 to 5 barrels and was being cleaned up. BP is currently facing a criminal investigation for a large oil spill which took place in March

“We regret that it is necessary to take this action and we apologize to the nation and the State of Alaska for the adverse impacts it will cause,” said BP America Chairman and President Bob Malone. “However, the discovery of this leak and the unexpected results of this most recent smart pig run have called into question the condition of the oil transit lines at Prudhoe Bay.”

The oil field accounts for 8 percent of the domestic output for the United States. The company said that the oil field would not be operational until both the company and regulators were satisfied that it would no longer pose a threat to the environment.

Oil prices shot up as analysts were speculating whether the firm would take months to restore full operation.