A gas pump is covered with an out of service message as fuel ran out ahead of Hurricane Harvey's arrival near the Texas coastal area, in Houston, Texas, U.S., August 25, 2017. REUTERS/Ernest Scheyder

(Story corrects final paragraph to say RFA requested the waiver on Monday, not Saturday in August 28 instance.)

WASHINGTON (Reuters) - The U.S. Environmental Protection Agency will lift as soon as Monday additional gasoline and diesel fuel requirements for more areas of Texas and for Louisiana to address potential shortages caused by Tropical Storm Harvey, a source familiar with the process told Reuters.

The waivers would allow the sale of gasoline that does not comply with regular environmental guidelines. The agency is also expected to expand the waiver to off-road diesel died red.

On Friday, the EPA granted a temporary waiver until Sept. 15 to help ensure an adequate supply of gasoline is available in areas directly affected by the storm until normal supplies could be restored. On Saturday, the EPA expanded it to include the Dallas area.

Harvey barreled into Texas on Friday as the strongest hurricane to hit the state at the heart of the U.S. oil and gas industry in over 50 years.

EPA spokeswoman Liz Bowman said the agency approved waivers for Louisiana but she could not confirm any others.

A source told Reuters that the agency will also deny a request by the Renewable Fuels Association, a lobby group for the biofuel industry, to expand a fuel waiver to relax limits for ethanol blends, in response to Harvey.

In a letter to EPA Administrator Scott Pruitt sent on Monday, the RFA asked EPA to relax Reid Vapor Pressure (RVP) limits to 10 psi for all finished gasoline blended with ethanol in conventional and reformulated gasoline areas nationwide, through Sept. 15.