NEW YORK (Reuters) - A former vice president of Citigroup Inc was charged on Monday with embezzling more than $19 million from the company's accounts.

Gary Foster, 35, was arrested on Sunday at New York's Kennedy airport on a flight arriving from Bangkok, prosecutors said. He was scheduled to make his initial appearance Monday afternoon in Brooklyn federal court, where he would plead not guilty to the charges, according to his attorney, Isabelle Kirshner.

Between May 2009 and December 2010, prosecutors said, Foster transferred $19.2 million from Citigroup debt-adjustment and interest-expense accounts to his own personal bank account at JPMorgan Chase.

Foster put fake contract and deal account numbers in the wire-transfer instructions to make them seem like they were supporting an existing contract, before diverting them first into the bank's cash accounts and then into his own accounts in as many as eight separate transfers, prosecutors alleged.

"The defendant allegedly used his knowledge of bank operations to commit the ultimate inside job," said U.S. Attorney Loretta Lynch.

The alleged fraud went unnoticed until a recent internal audit of Citigroup's internal treasury department. A Citigroup investigator immediately informed the authorities, according to an affidavit from Thomas D'Amico, a special agent with the Federal Bureau of Investigations.

A representative for Citigroup said the bank was "outraged" by Foster's alleged actions.

"Citi informed law enforcement immediately upon discovery of the suspicious transactions and we are cooperating fully to ensure Mr. Foster is prosecuted to the full extent of the law," the bank said in a statement.

(Reporting by Jessica Dye; Editing by Gunna Dickson and Steve Orlofsky)