The NFL and its referees' union have agreed to federal mediation.

George Cohen, director of the Federal Mediation and Conciliation Service, will conduct the talks between the on-field officials and the league. Cohen also mediated between the NFL and its players' union before last year's lockout.

No dates or sites have been announced for the mediation, and NFL spokesman Greg Aiello says, "The goal is to negotiate an agreement."

The officials' contract with the league expired after the 2011 season. The NFL is looking into replacement officials if a new deal is not reached by the preseason.

In 2001, replacement officials were used for one preseason game and the first week of the regular season before a contract was finalized.