MILWAUKEE (AP) _ Green Bay Packers quarterback Brett Favre cooperated with an FBI sting operation that resulted in two men being charged with selling more than 1,000 phony Favre autographs, a prosecutor said Monday.

Assistant U.S. Attorney Steven Biskupic disclosed Favre's role in the probe during a federal court hearing in which a second man charged in the case pleaded guilty.

``Brett feels bad about the whole incident _ and he really feels bad for the little kids who thought they were getting real autographs,'' said Joe Sweeney, Favre's marketing agency.

Biskupic said the sting operation started after authorities got a tip last year that Ron Marth, a sports memorabilia dealer from suburban Mequon, was selling phony Favre autographs.

An undercover officer gave Marth 50 photos of Favre and asked if he could get the quarterback to sign them.

Marth promised to get the photos signed for $3,750, Biskupic said.

When Favre appeared at an autograph show organized by Marth in November, Marth asked Favre to sign five of the photos, but Favre declined, as arranged in advance.

Even though he didn't sign any photos, Marth returned the 50 photos to the officer with ``Brett Favre 4'' scrawled on them.

Favre, shown the autographs, said they were not his.

Marth, 53, has pleaded guilty to fraud charges in exchange for a recommendation from prosecutors that he be sentenced to only one year in prison.

Rex Valenti, 26, of West Allis, charged in the same case, pleaded guilty to one count of aiding and abetting a wire fraud.

Biskupic said that because of Valenti's cooperation with investigators, he likely would face about six months in prison.