According to Spanish newspaper El Mundo Deportivo, new Barcelona manager Luis Enrique has informed both Song and Afellay that they will not play a minute of meaningful action next season if they refuse to leave the club.
Dutch international Afellay has struggled with injuries since his move to the Nou Camp in 2011, and the 28-year-old has been linked with a move to Turkish side Besiktas. He can leave for free at the end of the season but Barca want him off the books now.
Song meanwhile, has been linked with Chelsea and Manchester United already this summer - with a return to former-club Arsenal not completely out of the question. The Gunners are looking for another midfielder, having sounded out interest in Real Madrid star Sami Khedira and Sporting Lisbon youngster William Carvalho.
Song at Arsenal
Cameroonian international Song was a big hit at the Emirates Stadium, earning his move to Barcelona in the summer of 2012. But he's failed to nail down a starting place, and even a brief experiment at centre-half did little for his chances with the Spanish giants.
But while Barca can offload Afellay next summer at the very latest, Song is reportedly under contract until the end of the 2016/17 season.
And he's on a big wage too, which means it's proving difficult for Barca to find a suitor. Enrique has sought to encourage Song to consider his options away from the Spanish giants, telling him that he will face a season training with the reserves if he doesn't find another team.
Chelsea or United to move?
Chelsea boss Jose Mourinho has insisted that his business is complete, but with John Obi Mikel linked with a move away and Oriol Romeu out on loan again, the Blues manager could be tempted back into the market if the price is right.
The same goes for Manchester United, who addressed their central midfield need with the addition of Ander Herrera from Athletic Bilbao. But Louis Van Gaal too is thought to be planning more additions, and Song has the Champions League experience and is the right age, 26, to make a difference at Old Trafford.