The club have ruled out Team GB coach Pearce picking Rio Ferdinand, Wayne Rooney, Paul Scholes and Jonny Evans for the Olympic tournament at London 2012 as over-23 players.
According to a 2008 court ruling, clubs have the right to refuse to release players for the competition as it is not on the international calendar, but United are only taking that position on their over-age players.
Tom Cleverley, Danny Welbeck, Phil Jones and Chris Smalling could be part of the Olympic squad if they are not picked for the England Euro 2012 squad.
It can be revealed that United boss Sir Alex Ferguson, who on Thursday said that striker Javier Hernandez will not be part of the Mexico Olympic team at the Games, will not stand in the way of Giggs being part of the Olympic squad as the 38-year-old has never played in a major international tournament.
Giggs has indicated he would accept an invitation - each squad are allowed three over-age players - so long as the Football Association of Wales did not oppose him doing so. Sources there have confirmed that while they are politically opposed to a GB team, they would not prevent Giggs taking part.
An FA spokesman refused to confirm whether they had received the letter from United.
The prospect of a row, or even a legal battle, looks unlikely however, especially given United's acceptance that young players not involved in Euro 2012 plus Giggs can be selected.
In relation to Hernandez, who had initially been selected as an over-age player for Mexico, United said they had agreed with the Mexican FA that the striker, who turns 24 on June 1, has the full summer off.
Ferguson told the club's website: "His form last season was fantastic. He's found the second year more difficult, but a lot of that is down to not having a summer break for three years and playing every summer for his country."
Source: PA
Source: PA