A Qantas flight from London to Singapore was stopped from flying into Iraqi air space.
A Qantas spokeswoman told AAP that Iraq air services would not allow the flight into Iraq air space on Monday as they did not "recognise the authority" who had pre-approved the flight path.
The QF32 flight had to divert to Dubai to refuel in order to allow for a different flight path.
Qantas said the airline had been flying on this route for some weeks and didn't know why this incident had now occurred.
The Australian carrier is now liaising with Iraqi authorities to investigate why the plane had been denied entry.
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The QF32 is the same flight number of the A380 Airbus which suffered an engine explosion flying from Singapore to Sydney on November 4 2010.
The pilot managed to land the plane and nobody was injured in that incident. Qantas is now completely confident Rolls Royce has fixed the engine fault on that jet.
