The Morocco midfielder joined Boro from Hibernian on transfer deadline day on a three-year contract but has returned to his homeland while he awaits a visa.
Boss Tony Mowbray also added Bayern Munich II captain Maximilian Haas to his squad on deadline day but it remains to be seen whether the defender will feature.
Mowbray's side were not in action at the weekend as they were knocked out of the FA Cup in the third round and they have since lost midfielder Gary O'Neil to West Ham.
Seb Hines is set to keep his place in the centre of Boro's defence after impressing against the Lilywhites, partnering Matthew Bates following David Wheater's move to Bolton.
Source: PA
Source: PA