"We had a world-class corrosion monitoring and spill detection system, much better than required by regulation. It worked, it continued to work, but there was an event," Browne said in an interview late Thursday.

"We are now responding by making standards even higher than those mandated anywhere in the world," he added.

The spill came less than a year after a blast at BP's big refinery in Texas City, Texas, killed 15 people and injured scores more, dealing a blow to its reputation in the United States and prompting a government investigation.

The United States Environmental Protection Agency's criminal investigations arm has convened a federal grand jury to determine whether there is enough evidence to charge BP with a crime over the Alaska spill.

BP says it is cooperating with the investigation and, when asked if he thought there was any possibility BP could be held criminally liable for the spill, Browne replied emphatically, "I certainly don't."

The EPA investigation into the spill comes as the US Department of Transportation said on June 5 that it believed BP's corrosion management practices were unsound.

BP was ordered to clean the pipelines by mid-June, but the company has been unable to comply, arguing that the large volume of sediment in the pipelines makes it impossible to clean them quickly.

Company officials say the government's decision this week to allow the company to continue operating its Alaskan pipelines without immediately cleaning them should be taken as a sign that the federal authorities are still confident in BP's ability to operate the lines safely.

TEXAS CITY

The spill probe added to the already intense scrutiny BP was facing from regulators following the Texas City explosion. The company has been fined US$21.4 million by federal workplace safety regulators and has paid more than US$500 million in compensation to many of the victims and their families.

The accident raised questions about the safety culture within BP. While the company has taken responsibility for the accident, it says the cause of the tragedy was the failure of refinery employees to follow written procedures.

The union at Texas City has argued that BP management should share some of the blame and the Chemical Safety Board, a federal agency, is currently investigating the accident.

The CSB is interviewing BP managers and may even interview Browne, who said BP was taking steps to improve the supervision of operating units by country heads and other senior managers.

"BP is a highly decentralized company, so authority is delegated to the appropriate level, and with that authority comes responsibility," Browne said.

"The real question is whether or not the checks and balances are effective. We've made a big action, which is to completely change the way in which we do our audit, to make sure that we don't have anything that could be ignored."

BP's internal safety data will now be more oriented toward tracking "near misses" and other leading indicators of potential safety problems, Browne explained.

"Texas City broke an extraordinarily good safety track record for BP, both in the United States and worldwide. We responded very rapidly to that event and we have both applied the lessons learned from that event at Texas City and elsewhere in the United States and worldwide," Browne said.