The forces of the Libyan military strongman Gen Khalifa Haftar say they will target any civilian or military plane using the airport that serves the capital, Tripoli.
A spokesman said this was a final warning.
Earlier rocket fire had forced Mitiga airport to close.
Gen Haftar’s forces accuse Turkey of using it as a base from which to target them.
The Turks give military support to Libya’s UN-backed government, which holds Tripoli.
For many months Gen Haftar has been waging a major offensive aimed at capturing the city.
