The United Kingdom's Serious Fraud Office ordered drug makers GlaxoSmithKline and AstraZeneca to turn over its documents that were related to its dealings in Iraq. The move is part of the SFO's probe into the UN oil-for-food program.

Aside from the two British drug firms, the $44.2 million (22 million pound) investigation includes a number of British infrastructure companies.

The probe is in response to the 2005 UN report by Paul Volcker, former chairman of the U.S. Federal Reserve, that listed over 2,200 companies worldwide alleged to have bribed the Iraqi government in exchange for contracts under the UN oil-for-food program. Under the program, Iraq was allowed to sell limited volumes of oil to purchase food and medicine from foreign companies.

Among the documents that the SFO is asking from the two drug makers are emails, faxes, contracts and invoices.

GSK, in a statement, said its employees and agents in Iraq did not knowingly engaged in any wrongdoing. AstraZeneca admitted it received a disclosure request for SFO and pledged to fully comply. A third multinational drug firm based in the U.S., Eli Lilly, was similarly asked by the SFO to produce documents. Eli Lilly has an office in the U.K.

The report alleged AstraZeneca paid $162,000 (81,000 pound) as bribe to get three contracts worth $2.9 million, while GSK reportedly paid $1 million to win nine pharmaceutical contracts worth $11.9 million.