The statement on the oil ministry's website confirmed that the fourth bidding round for energy contracts would be held from May 30-31, and said that "the final list of prequalified companies includes a total of 47 entities, split between operators and non-operators."

Exxon was not on the list given in the statement.

Asked about the Exxon situation, Abdel Mehdi al-Amidi, the director general of the oil ministry's petroleum contracting and licensing directorate, said: "You have the statement and it contains the list of companies, and you know the story of ExxonMobil." He declined to comment further.

Iraq's autonomous Kurdistan region on October 18 inked a deal with ExxonMobil for it to explore six areas, but Baghdad regards any contracts not signed with the central government as invalid.

Before signing the Kurdistan contract, Exxon had already made an oil deal with the central government.

In January 2010, the Iraqi oil ministry completed a deal with ExxonMobil and Anglo-Dutch giant Shell to develop production at West Qurna-1. With reserves of about 8.5 billion barrels, it is the country's second largest oilfield.