NEW YORK — Lawyers for a former IBM senior executive said Tuesday that an intimate relationship with a hedge fund company employee who later “played” him led him to feed her confidential information that resulted in his insider trading arrest.

In court papers submitted in federal court in Manhattan, lawyers for Robert Moffat blamed an affair with fellow defendant Danielle Chiesi for behavior that led him to plead guilty to securities fraud and conspiracy to commit securities fraud. They asked a judge to sentence him to probation on Sept. 13.

Moffat, 53, of Ridgefield, Conn., was charged along with 20 others in what prosecutors have called the largest hedge fund insider trading case in history. Moffat was once considered a candidate for chief executive officer at IBM.

“That fact that what began as a professional relationship between Ms. Chiesi and himself became intimate is a transgression that haunts Bob terribly,” the lawyers wrote.

They said Moffat met Chiesi in 2002 and over time the “relationship with Ms. Chiesi became an intimate one.”

As a result, they said, Moffat on several occasions in 2008 provided Chiesi with information about three companies, including IBM. At the time, Moffat was senior vice president and group executive at International Business Machines Corp.’s Systems and Technology Group.

The lawyers said Chiesi was careful not to tell Moffat that she was trading on the information.