Iraq will issue invitations to international energy companies to show interest in new gas exploration contracts in a fourth bidding round, with responses due on May 19, an Iraqi oil official said on Wednesday.

Iraq said last month that 12 exploration blocs, including the first sea exploration bloc, would be tendered in the auction, to be held in November.

"We will publish a statement on Thursday to start inviting oil and gas companies to sign up for the fourth bidding round. We set May 19 as a deadline for answering the invitation," Abdul-Mahdy al-Ameedi, head of the Oil Ministry's licensing and contracting office, told Reuters.

Ameedi said around 46 pre-qualified companies will be able to take part in the gas auction, especially companies that have signed development contracts.

Companies that plan to take part for the first time or that were not qualified before need to submit required documents on their legal and financial status, he added.

Iraq is seeking to boost its oil and gas reserves through exploration contracts and expects to add 29 trillion cubic feet of gas and 10 billion barrels of crude as additional reserves.

Opec member Iraq sits on the world's fourth-largest oil reserves and flares around 700 million cubic feet of gas every day at its southern oilfields.

It needs to harness that energy to generate electricity and end chronic power blackouts that still plague the country almost eight years after the U.S.-led invasion that ousted Saddam Hussein.

Iraq auctioned three major natural gas fields to foreign firms last October.-Reuters