The sources said that two airliners had taken off from Cairo en route to Sanaa but later had to fly back.
"At about 5-6 a.m. the planes took off but approaching Saudi Arabia’s air space, they were denied access to fly through [the kingdom’s airspace] without explanations in response to a flight permit request," they said adding that both planes had to return to Cairo.
An underway military operation seems to be behind Saudi Arabia’s decision.
At Cairo’s air hub the permit is expected by Sunday so that the airliners can leave for Sanaa in the morning.