Slimani is in Spain with his Newcastle United team-mates ahead of tomorrow's friendly at the Pinatar Arena.
However, the striker, signed on loan from Leicester City in January, has been restricted to gym work at the club's Algorfa base.
Slimani will link up with his Algeria team-mates next week ahead of games against Tanzania and Iran.
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United manager Rafa Benitez said: "He was not training with the team, so he will not be part of the team tomorrow.
“Islam's progressing with our medical staff, and we're talking with the medical staff of his national team, so it makes sense.
“Hopefully, he will progress in the days ahead. It's not ideal, but we can’t stop them or stop him playing (for Algeria).
“At the same time, we want him to play to be sure he is a little bit better if he has to play against Huddersfield (on March 31).”