Malaysia Airlines has come under renewed criticism for flying a passenger jet to London over war-torn Syria in order to avoid using Ukrainian airspace.
The news comes just days after Malaysian Airlines flight MH17 from Amsterdam to Kuala Lumpur was shot down by a missile over the conflict zone in eastern Ukraine, killing 298 people. It was one of the deadliest attacks ever made on a commercial airliner.
The route of Sunday's flight MH004 over Syria from Kuala Lumpur was revealed in a tweet by aviation web service Flightradar24.
However, the airline immediately responded by confirming that it was following existing airline guidelines. In a statement, it said: "MH004's flight plan is in accordance to the International Civil Aviation Organisation's approved routes," pointing out that Syrian airspace was not subject to restrictions.
"At all times, MH004 was in airspace approved by ICAO," it said. "Malaysia Airlines maintains that the safety of its passengers and crew is of utmost priority."
The rerouting over another conflict zone has highlighted the difficulties airlines face in finding routes in an already crowded airspace between Asia and Europe.
Current guidelines mean that individual airlines have discretion to plan flight routes along air routes they think are safe, relying on governments to issue warnings if they deem airspace unsafe. Many factors come into play when deciding these routes, including the possible extra costs for rerouting.
FlightRadar24's findings show that on the two days following the downing of flight MH17, Malaysia Airlines' Kuala Lumpur to London flight MH004 took a route over eastern Turkey, avoiding Syria and the Ukraine. It is not yet clear why its path changed to cross Syria on Sunday.
The Flight Safety Foundation has called on the International Civil Aviation Organisation to hold a review the systems in place to warn airlines of hostile airspace, reports the Wall Street Journal.