Half  the 4,500 companies that took part in the United Nations oil-for-food programme in Iraq allegedly paid kickbacks or illegal surcharges and are being given a chance to respond to the charges, two top investigators said.

The UN-backed probe will wrap up its work with a major report in early September on the USD 64 billion operation and a final report in October on the companies involved in the purchase of Iraqi oil or sale of humanitarian goods under the programme, the investigators told Associated Press.

"We will report on the management and the corruption," former United States Federal Reserve chairman Paul Volcker, who heads the investigation, said in an interview on Monday. "We will talk about the benefits and the shortfall."
    
The oil-for-food programme, launched in December 1996 to help ordinary Iraqis cope with UN sanctions imposed after Saddam Hussein's 1990 invasion of Kuwait, was one of the largest humanitarian programmes in history.

By most accounts, it achieved what it set out to do, becoming a lifeline for 90 percent of the country's population of 26 million.
    
Under the programme, Saddam's regime could sell oil, provided the proceeds went primarily to buy humanitarian goods or pay war reparations.

Saddam allegedly sought to curry favour by giving former government officials, activists, journalists and others vouchers for Iraqi oil that could then be resold at a profit.

Volcker said 'the definitive list' of more than 4,500 private contractors involved in the programme will include for the first time, the entities behind so-called front companies.