The German-born Reds centre-half hasn’t played for Cameroon since the 2014 World Cup in Brazil and he said he didn’t want to play for the national team for the moment because of a “bad experience” with the previous coaching staff.
"These players have put personal interest above those of the national team and the federation reserves the right to take action against the players in accordance with FIFA regulations," said Cameroon manager Hugo Broos in a statement on Tuesday.The other six of Andre Onana of Ajax, Nancy’s Guy Roland Ndy Assembe , West Brom’s Allan Nyom, Maxime Poundje of Bordeaux, Andre-Frank Zambo Anguissa of Marsaille and Lille’s Ibrahim Amadou.
All seven had earlier this month been named in a preliminary list of 35 for January’s African Cup of Nations, where Cameroon are drawn in Group A with the hosts, Burkina Faso and Guinea Bissau.
Cameroon's football federation can ask FIFA to suspend the players at club level for the duration of the tournament, which ends on Feb. 6, if they so desire.
Broos, who took over in February, has twice been to see Matip to try and persuade him to return to the side but so far he has been unable to change his mind.
Nyom told Broos he wanted to stay at West Bromwich Albion to keep his place in the team, a sentiment shared by Amadou, Ndy Assembe, Onana and Zambo Anguissa.
Poundje, uncapped by Cameroon, said he preferred to set his sights on playing for France. Cameroon are to name the final 23-man squad for the tournament next week.