Close to the pipeline's midpoint, about 50 miles (80 km) north of Fairbanks, oil sprayed from the puncture to coat about two acres (0.8 hectares) of ground in an area of tundra and stunted spruce, operator Alyeska Pipeline Service Co. said.

An estimated 6,600 barrels, or 277,000 gallons, gushed from the bullet hole, Alyeska said. Oil continued to spew last week. The hole had not been plugged because of the high pressure in the line at that section, Alyeska said.

The company does not yet have a time estimate for the plugging, spokesman Tim Woolston said.

Alyeska has isolated the affected section of pipeline, which held about 20,000 barrels, or 840,000 gallons, of oil at the time of the leak, Woolston said. The amount has declined since then, he said. "Since early on, we have been draining the line slowly," he said.

CLEANUP PROCEDURE IS DESCRIBED

About 120 emergency workers were dispatched to the scene, along with representatives of regulatory agencies, the Alaska Department of Environmental Conservation said. Workers were setting up containment areas to collect the spilled oil and using vacuum trucks to suck it up and remove it, the conservation department said.

Woolston said the cleanup workers had picked up 357 barrels, or nearly 15,000 gallons, by midafternoon.

"The contamination is limited to a two-acre area, and it is limited with containment dikes and ponds that have been put in place," he said. "It has been described as a very stable situation, even though oil is still coming out of the line."

No animals and fish appeared to have been directly affected by the spill, the department said.

The Alaska State Troopers arrested a local man, Daniel Lewis, 37, for allegedly shooting the pipeline. He was charged with first-degree criminal mischief, driving while intoxicated, assault and misconduct involving a weapon and was jailed in Fairbanks, trooper spokesman Greg Wilkinson said.

The pipeline was built to withstand gunshots and has been hit by bullets in the past. But none had previously pierced the thick pipe's protective layers, which Woolston said consisted of an outer coating of galvanized metal, four inches (10 cm) of insulation and a half-inch (1.25 cm) of steel.

Wilkinson, the trooper spokesman, said merely that the pipeline had been fired on with "a high-powered rifle." A local television station identified the alleged weapon as a .338-caliber rifle. Ammunition that size is used for hunting large American and African game.

ALMOST ONE-FIFTH OF U.S. OUTPUT

Producers that depend on the pipeline to transport their oil halted nearly all output from the North Slope, which industry and state sources say usually accounts for about 18 percent of overall U.S. output.

Production last week was only 5 percent of normal, according to representatives of the two companies operating the oil fields there, BP unit BP Exploration (Alaska) Inc. and Phillips Petroleum unit Phillips Alaska Inc.

Alyeska is owned by companies with interests on the North Slope. Major owners are BP, Phillips Petroleum and Exxon Mobil.

At the southern end of the pipeline, the shipping of stored oil can continue as normal for at least a day, Woolston said.

"There is enough oil in storage to continue loading operations as normal until Sunday," he said.

The spill could add to the debate about oil exploitation in Alaska, where President George W. Bush wants more exploration despite environmentalists' opposition.