Babel's call up has not pleased Rafael Benitez who is already losing Javier Mascherano, Lucas Levia and has Emiliano Insua on Argentina's reserve list.
"Obviously, we are really pleased that Ryan has come back to training because he is an important player for us and he has worked hard to recover from the injury he suffered with Holland," said Benitez.
"But we are really worried because after getting him fit we will lose him again. This is a big problem - we prepare him and then he goes away with the national team.
"This season is very important for him. In his first season he was settling in but this time he has more experience and we are looking for him to give something from the beginning, so it is really important for him to start working with his team."
