Eni SpA (E), Italy 's biggest energy company by market value, said Thursday that Milan prosecutors are conducting an investigation on whether behavior by company employees resulted in illicit activities related to the awarding of contracts in Iraq .

The accusation is of criminal conspiracy and corruption and in relation with Eni Zubair SpA's activity in
Iraq and of Saipem SpA (SPM.MI) in the "Jurassic" project in Kuwait , according to Eni's annual 20-F filing to the SEC, released Thursday.

Eni said an employee of subsidiary Eni Zubair has resigned and the company is reserving the right to take legal action against the former employee to defend its interests.

The Rome-based company said it and Eni Zubair had no involvement with the alleged illicit activities that magistrates are accusing it of.

Eni said it commissioned an external consulting firm to perform an audit into the matter and that it still isn't concluded.

The 20-year Zubair service contract was awarded at an Iraqi licensing auction held in 2009 to the Eni-led group, which also includes U.S. Occidental Petroleum Corp. (OXY) and Korea Gas Corp. (036460.SE), or Kogas.

The Zubair field--one of the largest of
Iraq 's oil fields--was producing 195,000 barrels a day before it was awarded to the Eni-led group. Production has since reached about 250,000 barrels a day and is expected to rise to a level of 1.125 million barrels a day in coming years as the full field development plan is completed.

Saipem, the oil-services company which Eni controls, also commenced through its internal audit department an internal review with the support of an external consultant, said Eni. It added that the review didn't find any irregularities or elements against one of its employees from a criminal point of view.

The unnamed individual is still a Saipem employee, although moved to a different function, it said.

At the start of March,
Milan prosecutors notified Saipem of a request of extension of the preliminary investigation, Eni said in the filing.