A Houston oil trader pleaded guilty yesterday in New York to federal fraud charges in connection with illegal profits and kickbacks involving the United Nations oil-for-food program in Iraq during Saddam Hussein’s rule.

The trader, David B. Chalmers Jr., admitted that he and two companies he ran, Bayoil USA and Bayoil Supply and Trading, made millions of dollars in kickbacks to the Iraqi government  as well as huge profits  while trading oil under the $65 billion aid program.

In April 2005, Bayoil USA became the first American company to be indicted in the wide-ranging criminal investigation of the program, which was established by the United Nations in 1995 to ease some aspects of the sanctions imposed on Iraq after it invaded Kuwait in 1990. Under it, Mr. Hussein’s government could use the money from limited oil sales to buy supplies like food and medicine.

The authorities said Bayoil and Mr. Chalmers not only made illegal payments to get Iraqi oil but also conspired to artificially lower its price, thus depriving the Iraqis of money for items they sorely needed. A man described by the authorities as an associate of Bayoil, Ludmil Dionissiev, a Bulgarian oil trader living in Houston, also pleaded guilty yesterday to charges of fraud and conspiracy in the case.