DUBAI - Gulf military leaders on Thursday condemned the use of their countries' airspace to carry out attacks last month against a Saudi crude processing plant, a statement that indicated oblique backing for a U.S./Saudi account blaming Iran for the attack.

Attacks on Sept. 14 hit major oil processing facilities at Abqaiq and Khurais belonging to Saudi oil giant Aramco, causing a spike in oil prices, fires and damage that halved the crude output of the world's top oil exporter.

Yemen's Houthi group claimed responsibility for the attacks but a U.S. official said they originated from southwestern Iran and Riyadh blamed Tehran. Iran, which supports the Houthis in Yemen's war, has denied any involvement in the attacks.

Chiefs of Staff of the militaries of the Gulf Cooperation Council, which includes Saudi Arabia and five of its smaller neighbours, met on Thursday at Riyadh's request.

They condemned last month's attacks and other prvious strikes on Saudi oil infrastructure, and earlier attacks on shipping in the Gulf.

Their statement also condemned "the violation of some GCC countries' airspace to carry out the recent attacks on the kingdom".

That supports Washington's account of the attacks, since evidence that missiles or drones used to hit Saudi Arabia had passed through the air space of one of its Gulf neighbours to the east could prove they did not come from Yemen to the south.

The military heads emphasised the principle of collective security, called for unified efforts between their armed forces and expressed support for actions taken by Saudi Arabia or any other GCC country to defend their territory.

(Writing by Lisa Barrington; Editing by Hugh Lawson) ((lisa.barrington@thomsonreuters.com;))