Song joined Barcelona 2 years ago but has failed to break Xavi, Andres Iniesta and Sergio Busquets monopoly on midfield places.
This season he has made just 11 league appearances under new manager Tata Martino, and with his Barcelona future not looking any more assured under the new manager, Marca claim that the Cameroonian international has been transfer listed.
It is believed that Barca will only seek £15m for the player, the price they paid for Song in 2012 but a number of clubs are also looking at him including Man City and former club Arsenal.
United reportedly rejected the chance to sign Song last month, instead preferring to focus their attention on Juan Mata. But with Mata secured Moyes could be tempted to move for the 26 year old, especially at that price considering the fees being thrown around for some of his other reported targets.