"Sekou is an athletic and mobile player who has trained with us and looks a very good footballer," Royals director of football Nicky Hammond has said.
"West Ham were keen to sign him but want him to gain some experience here."
"I am appreciative to Alan Pardew that he has allowed him to join us. He will give us another option over the next few months."
The move is subject to approval from the Football Association, Premier League and Football League.