The 20-year-old joined the Spanish side on a season-long deal over the summer, but is frustrated at a lack of opportunities at Athletic Bilbao.
“His patience is being pushed and if nothing chances he will leave Bilbao in the New Year,” said San Jose’s agent, Jesus Medina.
“We do not understand Bilbao’s persistence to strike a deal over the summer if they had no plans to play San Jose.
“This situation is damaging to his career. He is a professional and does not want to cause controversy, but he is suffering at the moment.”
Blackburn and Wolves are both reportedly interested in signing the youngster on loan.