Cameroon's football association (Fecafoot) had previously threatened to take action against the absentees and can ask world soccer's governing body FIFA to suspend them from club football for the duration of the tournament, which ends on Feb. 6.
Liverpool said on Sunday that they had not received confirmation from FIFA that Matip was eligible for club selection.
"Liverpool... can confirm Joel Matip has been withdrawn from selection for today's Premier League fixture at Manchester United as the club continues to seek clarity from FIFA as to the player's eligibility," the club said on their website (www.liverpoolfc.com).
"The Cameroon Football Federation have failed to confirm that Matip can therefore play club football during the period of the Africa Cup of Nations.
"Liverpool have subsequently repeatedly sought, as a matter of urgency, clarity from FIFA in this regard.
"It is Liverpool's view that the player should be available for club football during the period of the competition and will continue to work for a speedy and unambiguous resolution."
Matip has not played for Cameroon since Sept. 2015.
(Reporting by Simon Jennings in Bengaluru; Editing by Toby Davis)
