WASHINGTON (Reuters) - Saudi Arabia participated in air strikes as part of a U.S.-led coalition against Islamic State militants over the weekend, a U.S. Department of Defense spokesman said on Tuesday.

U.S. Defense Secretary Ash Carter, who has been under pressure to shore up support from Sunni Arab allies to fight Islamic State last week welcomed a commitment from Saudi Arabia to expand its role in air strikes.

Saudi Arabia has concentrated its military efforts over the last year on the conflict in Yemen, where it is leading a coalition of mainly Gulf Arab forces battling Houthi fighters who control the capital, Sanaa.

"They (the Saudis) did participate in strikes over the weekend," said Peter Cook, a Pentagon spokesman, in a Tuesday news briefing. He did not say specifically what the Saudi actions were, or where.

The United States is leading a coalition fighting Islamic State insurgents, including through air strikes in Syria and Iraq.

Carter said last week that Saudi Arabia had committed to expand its role in the air campaign and the United Arab Emirates, another Gulf Arab country and U.S. ally, said it would restart its participation.

"We've seen so far in the Saudis' case that commitment turning into action in the last few days," Cook said.

(Reporting by Yeganeh Torbati; Editing by Bill Rigby)