Three Reds have had the options on an additional year, beyond the summer, triggered by the club.
Right-back Aaron Wan-Bissaka, centre-half Victor Lindelof and midfielder Hannibal are those in question, while talks with French duo Raphael Varane and Anthony Martial are continuing.
"We are talking with Rapha Varane and with Anthony Martial," the boss said at his press conference on Thursday. "And we have triggered the options on Aaron Wan-Bissaka, Victor Lindelof and Hannibal."
When pressed on Varane and Martial's situation, he replied: "I think that is an internal discussion between the club and the player.