The fire that halted about two thirds of Saudi Arabia's oil production last week cost the Arabian-American Oil Co. as much as $100 million in lost oil and burned equipment.

That was the assessment of Aramco Vice President George Larsen, who made the damage estimate in an interview published Thursday in the Saudi newspaper Al Riyadh. Larsen did not specify how much oil was lost or equipment burned, saying that more details would not be known until a committee investigating the fire makes its report.

The cause of the three-day fire is still unknown, but Aramco officials said they have ruled out sabotage because the pipe that broke and started the fire was under ground and could not have been sabotaged easily. The pipe ruptured at 3:30 in the afternoon in Saudi Arabia's eastern desert, and Armaco officials express doubt that sabouteurs were at work in broad daylight.

The worst damage was to a pumping station in the Abqaiq oil field, which shut down the flow of 6 million barrels of oil a day for three straight days and 5 million barrels of oil a day for the rest of the week.

Aramco said that by yesterday auxiliary pumps had raised the flow to about 80 per cent of the normal production of 9 million to 10 million barrels a day. Aramco said it expects the flow to be up to 90 per cent of normal by next week and to full production by the end of May.

A work force of 2,000 men is working around the clock to repair pipe, hook up bypass pipelines and install news pumps to replace damaged or destroyed pumps. Half the force are Aramco oilfield workers, the other half contractors pulled off the construction of a gas-gathering system.

While the oil flow has been curtailed, Aramco has been drawing from storage tanks on the Persian Gulf to help meet deliveries. The company has also had to cut back deliveries to major customers.

Exxon Corp. has told Japanese oil refiners it will cut deliveries to Japan by 30 per cent this month. Industry sources said that similar cuts will be applied to other customers in Western Europe and the United States.

Japanese oil refiners have said that they will increase purchases from Iran and Iraq and other refiners are expected to follow suit.