WASHINGTON - The U.S. Transportation Department (USDOT) said Saturday it is temporarily waiving truck driver hours of service rules after the unanticipated shutdown of the BP Whiting, Indiana refinery.

Reuters reported Friday the 435,000 barrel-per-day refinery was shut down and undergoing damage assessment following loss of electrical power and cooling water systems in a Wednesday fire, citing sources.

The exemption to maximum driving time rules for truck drivers applies to those transporting gasoline, diesel, jet fuel and other refined petroleum products to Illinois, Indiana, Michigan, and Wisconsin, USDOT said.

Michigan Governor Gretchen Whitmer's office on Saturday said she was working "to ensure continued access to an adequate supply of motor fuels by waiving regulations on motor vehicle hours-of-service rules, as the effects of the outage at the plant are expected to spread across the region and will impact drivers transporting such fuel."

Whitmer signed an executive order Saturday exempting motor carriers and drivers transporting gas and diesel from compliance with state maximum weekly driving and on-duty limits.

The order also temporarily suspends certain laws and regulations to accelerate the transition to the fall fuel supply and takes advantage of existing fuel stocks, contingent on the U.S. Environmental Protection Agency making similar changes.

EPA did not immediately comment Saturday.

Whitmer's office said Whiting provides approximately 20% to 25% of the refined gasoline, jet fuel, and diesel used collectively by Illinois, Indiana, Michigan, and Wisconsin.

"While efforts are underway to find ways to replace the supply from the Whiting refinery, disruptions in the fuel supply are likely," Whitmer's office said.

(Reporting by David Shepardson; Editing by Chizu Nomiyama and Nick Zieminski)