HATTIESBURG, Miss -- Three days after a conference call with Green Bay Packers team officials on Tuesday in which quarterback Brett Favre emphatically expressed his desire to play in 2008, Favre on Friday formally asked for his contractual release from the Packers in a letter, sources close to Favre and the team said.

The letter was sent by Favre's agent, James "Bus" Cook, via overnight mail on Thursday and arrived at the Packers facility Friday morning.

Cook, on behalf of Favre, expressed a desire to have an amicable parting, as the Packers have been reluctant to embrace his return. Favre announced his retirement in early March.

During a conference call on Tuesday that included Packers general manager Ted Thompson, Packers coach Mike McCarthy, Favre and Cook, sources say that the quarterback stated emphatically that he wanted to play again.

When Favre was reminded by the Packers' brass that it was in March when the quarterback said publicly and privately that he wasn't 100 percent committed to football, sources said. Favre acknowledged his state of mind at the time, but added that he never felt he was a 100 percent committed in March of previous years, either. Favre felt he had to make a decision to retire because the Packers were pressing him for an answer, a source said.

During the same conference call on Tuesday, neither Thompson nor McCarthy were openly receptive or enthused about Favre's desire to un-retire, the sources said, prompting Favre to direct Cook to request his release from the Packers. Favre has three years remaining on his contract for a total of $39 million. He currently is on the reserve-retired list.

Favre wants a mutual parting rather than having to force the Packers' hand by writing a letter to request his reinstatement to the active 80-man roster. Under league policy, the team would have to comply or release him.

Cook's letter did suggest that Favre's accomplishments for the franchise merited the team honoring his request to be released, also asking that the action be taken "with no strings attached." Favre does not want to be traded, sources said, because he wants the freedom of choice to play for any other franchise.

Favre has been in communication with McCarthy during the past month about his desire to play but until this week had not spoken with Thompson.

Neither Thompson nor McCarthy were available for comment on Friday.

Favre did not wish to speak publicly about his situation when approached while working out Friday morning at a local high school in Hattiesburg. He appeared to be in excellent physical condition and threw the ball with ease, even throwing a football 50 yards "on a rope" with high school receivers. He has been throwing and running with the team for more than a month.

Favre was relaxed and in a positive frame of mind, joking and telling stories about himself, former teammates and coaches. He planned to continue working out next week.

Chris Mortensen covers the NFL for ESPN.