The Reds have been linked with the 22 year old Argentinian midfielder over the Christmas period and the latest news will fuel speculation about an imminent move.
"I must get out of here. I cannot stay at West Ham any more like this, without playing," said Mascherano. "At my age, my game will only stagnate if I do not get the chance to play.
"I came to England to do well, but I have not had the opportunities necessary to show what I can do.
"If I am not playing in the West Ham team, I will have to leave to continue my career with another side."