Iraqi Prime Minister Haider al-Abadi called Saturday for legal action over allegations that senior officials took millions of dollars in bribes to help major firms secure lucrative oil sector contracts.

Abadi instructed the country's anti-corruption commission to take "legal measures" and called for the judiciary to pursue prosecutions connected to the scandal, a statement from his office said.

The allegations of corruption came to light in an investigation by The Huffington Post and Fairfax Media, which reviewed thousands of internal documents from Monaco-based firm Unaoil.

The report "revealed the involvement of senior Iraqi officials... in corrupt deals and bribes related to oil contracts during the period of previous governments", the premier's statement said.

The investigation found that Unaoil agreed to pay millions of dollars to influence Iraqi officials including oil ministers Hussein al-Shahristani and Abdul Karim Luaibi, the former of whom also served as deputy premier for energy affairs, to help secure contracts for its clients.

Unaoil clients in the Middle East included Rolls-Royce, Weatherford, Petrofac, Clyde Pumps, Cameron/Natco, FMC Technologies, Saipem, SBM Offshore, MAN Turbo and Leighton Offshore, according to the report.

At a news conference on Saturday, Shahristani, who is currently minister of higher education, denied having had contact with Unaoil.

He also said in a statement that if the evidence on which the investigation was based is not turned over to the Iraqi government, it should file a defamation suit.

The report on oil sector corruption has already sparked action in Europe.

Authorities in Monaco searched Unaoil's headquarters and the homes of company officials and also questioned leaders of the firm, the principality said in a statement.

This was done at the request of Britain's Serious Fraud Office as part of "a major corruption case with international ramifications," the statement said.

On its website, Unaoil says that it "invests locally in frontier markets to provide local capabilities at international standards using leading technology."

"This has made us as the local partner of choice for larger international companies," it says.

Iraq is plagued by endemic corruption that has robbed the country of huge sums of money that could otherwise have been spent on development and services.

Abadi has announced a series of reform measures aimed at reducing government waste and curbing corruption.

But the powerful parties and politicians who benefit from the existing system have opposed the changes behind the scenes, and little in the way of lasting change has been achieved.

ak-wd/hc

FMC TECHNOLOGIES

SBM OFFSHORE

VOLKSWAGEN

PETROFAC

SAIPEM

ROLLS-ROYCE HOLDINGS