The Moroccan national team is unable to reach (the Algerian city of) Constantine because permission for their flight with Royal Air Maroc, the team's official transporter, has not been confirmed," the Morocco's FRMF football federation said in a statement.
It said the Confederation of African Football (CAF) had informed it last month that Algeria had issued "an authorisation in principle" for the flight.
But just 24 hours before the tournament starts on Friday, the FRMF said it "notes with regret that the definitive authorisation for the flight from Rabat to Constantine has unfortunately not been confirmed".
Algeria closed its airspace to all Moroccan flights in September 2021, the month after it cut off diplomatic ties with its rival, accusing it of "hostile acts".
That was the latest escalation in a long-running rivalry fuelled by the Western Sahara dispute and relations with Israel.
The Moroccan team, which made history last month by becoming the first African or Arab team ever to reach the semi-finals of a World Cup, have won the past two African Nations Championships.