“I didn’t want to waste any more time at 83 years old fooling with this operation,” he told reporters in the courtroom. “The quicker I got it over with, the better.”

Mr. Wyatt’s lawyer, Gerald L. Shargel, said the government had offered the deal, under which four of the five original charges were dropped in exchange for a guilty plea. Those included conducting financial transactions with Iraq, an enemy nation at the time, and violating a United States embargo on that country.

“The defense of a criminal case is complicated when the client is 83 years old,” Mr. Shargel said. “That was certainly taken into account. For the government to have offered this disposition at this point suggests both sides recognized the risks involved in having a jury decide it.”

Michael J. Garcia, the United States attorney in Manhattan, issued a statement within two hours of the plea that said, “When Oscar Wyatt agreed to defraud the oil-for-food program by making illegal payments to the Hussein regime, he traded the humanitarian needs of the Iraqi people for the satisfaction of his own greed and the greed of the former government of Iraq.”

Mr. Garcia’s office, which led the criminal investigation into the troubled program, has so far extracted guilty pleas from five other defendants and won conviction of one more. Some $16.5 million in illicit profits have been seized, money that officials plan to transfer to the Development Fund of Iraq. Under the oil-for-food program, established in 1996, Iraq was allowed to sell its oil despite sanctions imposed after its invasion of Kuwait. But all profits from the sales were to have been used for food, medicine or any goods needed to sustain the Iraqi population.