Fire raged yesterday along a major oil pipeline in Saudi Arabia, forcing the Arabian-American Oil Co. to shut down the pipeline and stop the flow of two-thirds of Saudi oil production to the Persian Gulf.

By 8 p.m. EDT last night, the fire had been burning for 12 hours and looked likely to last for at least two more days.

First reports were that one man had been killed by the fire, which halted the flow of 6 million barrels of oil that normally goes through the pipeline everyday.

Washington Post Correspondent Thomas Lippman reported from Dahran, ARAMCO headquarters about 40 miles north of the fire's location, that a subsidiary pipeline was open and able to move about 1 million barrels of the 6 million originally shut down.

The fire was along the pipeline that runs through the Abqaiq oil field, about 20 miles from the Persian Gulf.

The pipeline carries oil from the Ghawar field, the world's largest oilfield, to Ras Tanura a Persian Gulf port, where it is pumped into tankers for export to most of the industrialized world.

Saudi Arabia is the world's largest oil exporter, shipping 1.5 million barrels of oil daily to the United States, about 2 million barrels to Japan and between 5 and 6 million barrels to Western Europe.

ARAMCO officials said last night that if the fire lasts only two or three days and the pipeline can be reopened shortly after the fire goes out, it will have relatively little impact on world oil supply.

During the winter months, windstorms in the Persian Gulf often close Saudi ports to tanker traffic for two or three days. At such times, ARAMCO increases oil production and pipeline flow when the storms subside to make up the lost production. Saudi Arabia can produce 11 million barrels a day but normally holds it to 9 million.

ARAMCO officials said last night that the fire had been contained to an area no larger than four acres and that it would be allowed to burn itself out. Officials were fearful that any attempts to fight the fire with water would only float oil away from where it is burning and spread the fire to other pipelines.

The fire apparently began when one pipeline in a network broke early yesterday morning. Natural gas in the pipeline then exploded, and the fire spready quickly along the pipeline to a pumping station at Abqaiq.

The pumping station drives oil coming in along several different pipelines to the Persian Gulf. Once the fire had spread to the pumping station, several pipelines were shut down automatically because of damage to the pumps.

The biggest fear ARAMCO officials expressed last night was that the pumping station might have to undergo major repairs before its compressors could begin to pump oil through the network again. Repairs might take as long as a week, which could mean that importers of Saudi oil would have to turn to storage tanks to keep their own supplies moving.

ARAMCO Vice President James Knight said last night that the cause of the fire was still unknown and suggested that sabotage is not being ruled out.

"There have been some unexplained fires in Qatar recently," Knight said, referring to an oil-producing sheikhdom along the Persian Gulf. "But nobody is prepared to say this fire was anything but an accident."

The pumping stations are Saudi Arabia's security weak point, and Saudis have often spoken privately of their nightmares about protecting them in a crisis.

The pipeline broke right where numerous lines converge, which made the explosion and fire that followed the break much more serious than if the fire had been confined to a single pipeline.

Although the fire had been contained last night, it was still burning at the pumping station and along stretches of at least three different pipes. The ruptured pipeline had also spilled considerable oil on the ground before being shut down and that oil was still burning last night.

Aramco officials said last night that they have no idea when the fire would burn itself out. They said they would have a much better idea of what happened and what might lie ahead when day breaks in Saudi Arabia, six hours ahead of the United States in time.