Paris prosecutors have opened an investigation into suspected corruption by French companies involved in the U.N. Oil-for-Food program with Iraq, judicial officials said Tuesday.

Investigators will initially limit the probe to companies that paid surcharges on humanitarian contracts for trucks, medical equipment and other materials, the officials said.

An independent panel, led by former U.S. Federal Reserve chairman Paul Volcker, accused more than 2,200 companies from some 40 countries of colluding with Saddam Hussein's regime to bilk the U.N. Oil-for-Food program in Iraq of $1.8 billion. Some 4,500 companies took part in all.

The report cited 172 French companies, including truck maker Renault Vehicules Industriels, that allegedly violated the terms of the program between 2000 and 2003, when Saddam was ousted from power.

The French probe comes after investigating judge Philippe Courroye sent portions of the Volcker report and other documents to prosecutors, officials said. The investigation also centers on alleged misuse of corporate assets.

Courroye has been looking into the Oil-for-Food program for more than three years.

The Oil-for-Food program, established in 1996 with Iraq's economy crippled by U.N. sanctions, allowed Saddam to sell oil in exchange for humanitarian goods meant for his people.

Volcker's report, finalized last October, showed that Saddam sold oil to foreign countries in hopes of getting their support for lifting the sanctions, and enriched himself through kickbacks.