GREEN BAY, Wis. -- The Green Bay Packers have filed paperwork in an attempt to collect a portion of Martellus Bennett's signing bonus after they released him with the designation that he failed to disclose a medical condition.

The NFL Players Association told ESPN it is "aware of the situation and currently monitoring."

The Packers released him with that designation to strengthen their case to recoup their money. They gave Bennett a $6.3 million signing bonus as part of his three-year, $21 million contract during free agency this past offseason.

The Packers could have tried to get back the entire signing bonus, but considering Bennett played seven games, the stronger case would apply to the remaining $4.2 million that's prorated over the final two years of the deal. The case is expected to be heard by an arbitrator and would need to be settled before next season because of the salary-cap ramifications.

Bennett hinted that he was planning to retire during the Packers' bye week. When he returned from the bye, he took part in the first practice. He never practiced after that and appeared on the injury report with a shoulder injury.

Shortly after the Packers released him on Nov. 8 and the New England Patriots claimed him the next day, Bennett disputed that he withheld any injury information and criticized the team's medical staff, saying they were trying to force him to play. Several Packers players, both past and present, came to the defense of team physician Dr. Pat McKenzie, saying that if anything McKenzie is too conservative when it comes to clearing players.

Bennett was inactive for one game before the Packers released him. He later said he received multiple opinions that he needed surgery. He then played in two games for the Patriots before they placed him on injured reserve. Packers outside linebacker Clay Matthews said the Packers "all got a good laugh" that Bennett was able to play for the Patriots but not the Packers.