The Frenchman needs a liver transplant but took part in Sunday's session, while his Dutch teammate is drawing closer to a return following a lengthy spell on the sidelines
Afellay has been out of action since tearing the anterior cruciate ligament in his left knee in September, just days after recovering from a hamstring problem sustained in pre-season.
He had set foot on the training pitch for the first time last month and participated in Sunday's session.
It is understood, however, that it will still take some weeks before the Dutchman can return to action with the Spanish champion.
Meanwhile, Abidal, who missed Saturday's 2-0 victory against Sevilla, also took part in the session as he awaits a liver transplant.
Barca will host Granada on Tuesday in its upcoming La Liga fixture.