Shell said late Tuesday it had already begun initial steps to reopen the Buenos Aires refinery ordered shut down last week by regulators who said they found pollution in soil samples and that the plant lacked necessary permits and environmental impact studies.

The Environmental Secretariat said Tuesday that it had received a cleanup plan from Shell that included concrete measures for better storage, treatment and disposal of hazardous wastes.

"After seven days of closure, Shell has presented the Environmental Secretariat with a cleanup plan for contaminated areas and planned investments for environmental improvements," the secretariat said in a statement. "Tomorrow the closure order will be lifted."

A Shell spokesman, Reginald Thompson, said that refinery operators had received approval from regulators to relaunch fuel production.

"We'll take 96 hours to get back" to full operations, Thompson said. He had no immediate comment on the plan that Shell offered to environmental regulators and said the company would issue a statement later.

Regulators had accused Shell of drawing water from the nearby River Plate estuary without necessary permits, having deficient procedures for handling waste and lacking environmental impact studies.

The refinery in the Dock Sud district of southern Buenos Aires turns crude oil from Argentine fields into gasoline and diesel fuels for vehicles, and also processes jet fuel, lubricants, solvents and paving asphalt.

Shell supplies about 14 percent of the country's service stations and some analysts raised the possibility of shortages if the shutdown continued indefinitely. Company executives said they used fuel from storage to meet demand at service stations nationwide.

Shell executives and the government of President Nestor Kirchner have feuded publicly in the past. Kirchner in March 2005 called on consumers to boycott Shell service stations when the company tried to hike prices that the government seeks to keep under control.

(This version RECASTS to UPDATE with regulators announcing refinery closure order will be lifted Wednesday, ADDS details. corrects agency name to Environmental Secretariat sted Environmental Ministry thruout.)