UNITED NATIONS — A U.N.-appointed panel investigating corruption in the $64 billion U.N. oil-for-food program in prewar Iraq has reopened an investigation into whether U.N. Secretary-General Kofi Annan steered business to a Swiss company that once employed his son.

The move came less than a day after investigators obtained a 1998 memo written by a former executive of the Geneva company, Cotecna Inspection, claiming that Annan and his staff indicated support for the company's bid for a $10 million-a-year contract to oversee imports of humanitarian aid into Iraq.

Annan has denied knowing that his son's former employer was trying to do business with the United Nations before it won the Iraq contract. His spokesman, Fred Eckhard, yesterday questioned the veracity of the memo, noting that Annan "had no knowledge that Cotecna was a contender for that contract."

The U.N.-appointed Independent Inquiry Committee, headed by former U.S. Federal Reserve Bank Chairman Paul Volcker, said in a March 29 report that it found no evidence Annan used his influence to award contracts to Cotecna. But the committee yesterday said it was "urgently reviewing" the new information, and Reid Morden, its chief of staff, said "we will have to take a careful look at what this [memo] says."

The U.N. oil-for-food program was established in December 1996 to provide relief to ordinary Iraqis facing hardships as a result of U.N. sanctions, imposed on Iraq after its 1990 invasion of Kuwait. Under the program, Iraq was permitted to sell oil to purchase food, medicines and other humanitarian supplies.

While the program succeeded in boosting nutritional levels, it also provided Saddam Hussein's government with an opportunity to raise more than $2 billion in illicit proceeds by requiring trading partners to pay kickbacks in exchange for doing business in Iraq. The abuses triggered investigations by the United Nations, congressional committees and federal prosecutors.