Iraq has postponed the first day of highly anticipated tenders for eight major oil and gas fields due to a thick sandstorm that engulfed Baghdad on Sunday, the oil ministry said.

Ministry spokesman Asim Jihad said the ministry would begin announcing the winners of contracts to develop the fields on June 30 instead of June 29 because many executives had been unable to fly into Baghdad owing to the weather.

Jihad said the contracts might be awarded on one day instead of over two days.

Some of the world's biggest oil firms, like Exxon Mobil. Total and Royal Dutch Shell are competing for deals to develop the six oil fields and two gas fields in the war-weary country's first major tender since 2003.

Iraq has the world's third largest proven oil reserves, estimated at 115 billion barrels.-Reuters