Qantas jetliners will go out of their way to avoid flying over the Strait of Hormuz and Gulf of Oman after a US military drone was knocked out of the sky by an Iranian missile.

The change was announced on Friday, with a Qantas spokeswoman saying the route change would remain in place until further notice.

The security measure will mean a change to Qantas flights between Australia and London, however it is understood the impact on flying time will be minimal.

Dutch airline KLM announced a similar measure on Friday, as did Malaysia Airlines and Singapore Airlines.

Qantas flights cross the Middle East at around 40,000 feet.

The US has also barred American-registered aircraft from flying over Iranian airspace in the Persian Gulf and the Gulf of Oman.

The flight ban was implemented over Iran’s Revolutionary Guard shooting down a US military surveillance drone, affecting a region crucial to global air travel.

The Federal Aviation Administration warned of a “potential for miscalculation or misidentification” in the region after an Iranian surface-to-air missile on Thursday brought down a US Navy RQ-4A Global Hawk, an unmanned aircraft with a wingspan larger than a Boeing 737 jetliner and costing over $US100 million ($A145 million).

-with AAP