Some of the world's leading carriers including British Airways, Qantas and Singapore Airlines on Friday suspended flights over the Strait of Hormuz, as Iran-US tensions flare over the downing of a drone.
The suspensions came after the Federal Aviation Administration in the United States issued a Notice to Airmen (NOTAM) "prohibiting US-registered aircraft from operating over the Persian Gulf and Gulf of Oman".
The NOTAM was in response to "heightened military activities and increased political tensions that might place commercial flights at risk", an FAA statement said, as Tehran and Washington engaged in a war of words over Thursday's missile strike on the drone.
The FAA's notice applies only to US-registered airlines, and United Airlines said it was suspending its Newark-Mumbai service in response. But European and Asian operators were taking no chances.
"Our safety and security team are constantly liaising with authorities -- including the likes of the FAA -- around the world as part of their comprehensive risk assessment into every route we operate," a BA spokeswoman said.
Germany's Lufthansa followed suit in bypassing the Hormuz area.
Dutch carrier KLM said: "Safety is the top priority for KLM. The incident with the drone is reason not to fly over the Strait of Hormuz for the time being. This is a precautionary measure."
Australia's flag carrier Qantas said: "We're adjusting our flight paths over the Middle East to avoid the Strait of Hormuz and Gulf of Oman until further notice."