But Slot will have a full complement of internationals available for the Seagulls’ visit.
The Dutchman confirmed that Liverpool made the decision in conjunction with the Egyptian FA.
“The way we have worked is that there's a communication between all three - the player, the club and country,” he explained.
“That's nothing new. But FIFA have said December 15 is the last day a player has to be released.”
Salah has fallen out of favour under Slot this season and has come in for criticism after his lacklustre performances came to be associated with Liverpool’s dismal form.
He has tallied five goals and three assists in 17 appearances so far this campaign, and was left on the bench for Sunday’s defeat of West Ham.
Asked whether Salah was unhappy with being benched, Slot said: “Fair assumption and normal reaction for someone who can play for us.
“Of course, a player isn't happy he isn't playing, he wasn't the only one I can tell you.
“The way he behaved was as you would expect from the professional he is, he was very supportive for his team-mates and handled himself really well.
“You can't play that well every three days if you go with your emotions, but Mo is so disciplined. He will always be that top professional as he was the last few days.”