July 31 (Reuters) - Refiner Phillips 66 said on Friday its board of directors had approved a $10 billion increase to its share repurchase program.

U.S. refiners this year have enjoyed a boost from stronger fuel margins after the Iran war tightened global supplies of gasoline and diesel.

The conflict raised concerns over disruptions to Middle East fuel exports, lifting refining margins.

Phillips 66 said the remaining authorization under its current program was approaching its limit.

"The increased share repurchase authorization supports our commitment to long-term shareholder value, alongside our secure, competitive and growing dividend, disciplined capital investment and continued debt reduction," CEO Mark Lashier said.