UPDATE 2-Trump says he will probably allow E15 gasoline sales all year

(Recasts with Trump comments)

WASHINGTON, April 12 (Reuters) - U.S. President Donald Trump said on Thursday that his administration may allow the sale of gasoline containing 15 percent ethanol year-round in a bid to help corn farmers.

The Environmental Protection Agency currently bans the higher ethanol blend, called E15, during summer because of concerns it contributes to smog on hot days.

Gasoline typically contains just 10 percent ethanol.

"Were going to be going probably, probably to 15 and were going to be going to a 12-month period," Trump told reporters during a meeting with governors and lawmakers at the White House. "Were going to work out something during the transition period, which is not easy, very complicated."

The announcement comes as the White House seeks to appease both the corn industry and the oil industry, which have been clashing over U.S. biofuels policy.

Oil refiners have complained the U.S. Renewable Fuel Standard requiring them to add biofuels into fuel is too costly while the agriculture sector has warned against changes that would undermine ethanol demand.

Monte Shaw, executive director of the Iowa Renewable Fuels Association, said the proposed shift to year-round E15 sales would be "very exciting news."

Refiners shares fell after Trumps comments, with Andeavor down 2.7 percent at $110.02, and both Phillips 66 and Marathon Petroleum Corp also down. (Additional reporting by Chris Prentice and Jarrett Renshaw in New York Writing by Richard Valdmanis Editing by Steve Orlofsky and Matthew Lewis)