Iraq has again delayed an auction due this year for a dozen oil and gas exploration blocs, a top official said on Thursday, because bidders requested more time to analyse what was on offer.

The bidding round had initially been scheduled for this month but in October the oil ministry delayed the auction to early March.

On Thursday, the head of contracts at the ministry said the sale had been pushed back again to April 11-12.

"The companies wanted more time to read in detail and clearly understand the technical information," Abdul Mehdi al-Amidi told AFP. "For that reason, we decided to delay the process by one month, to give them more time."

Amidi insisted that the ministry was ready to conduct the auction but had delayed it at the request of prospective bidders.

Iraq first announced the sale, the fourth of energy contracts to foreign majors since 2009, in April 2011. A total of 12 exploration blocks are on offer -- seven gas and five oil.

The blocs are located in the provinces of Basra, Najaf, Babil, Muthanna, Diwaniyah and Dhi Qar, south of Baghdad, Nineveh and Diyala to the north and Anbar to the west.

Iraq is looking to dramatically ramp up its energy output, as crude sales account for the vast majority of its government revenues. Baghdad currently exports around 2.2 million barrels per day of oil (bpd), with that figure set to rise by 300,000 bpd early next year.

The government says it will be capable of producing 12 million bpd by 2017, from current output of 2.9 million bpd.