Commercial airlines on Wednesday rerouted flights crossing the Middle East to avoid possible danger amid escalating tensions between the United States and Iran.

The flight restrictions reflected fears that the conflict between the longtime foes could ratchet up following Iranian ballistic missile strikes on two Iraqi bases that house US troops.

Those strikes were retaliation for the US killing of Iranian Revolutionary Guard Gen Qassem Soleimani in a drone strike near Baghdad last week.

Read more: Pakistan, India among countries urging nationals to refrain from travelling to Iraq

Australian carrier Qantas said it was altering its London to Perth, Australia, routes to avoid Iran and Iraq airspace until further notice.

The longer route meant that Qantas would have to carry fewer passengers and more fuel to remain in the air for an extra 40 to 50 minutes.

Malaysia Airlines said that due to recent events, its planes would avoid Iranian airspace.

Singapore Airlines also said that its flights to Europe would be rerouted to avoid Iran.

The US Federal Aviation Administration (FAA) said it was barring American pilots and carriers from flying in areas of Iraqi, Iranian and some Persian Gulf airspace.

The agency warned of the potential for "miscalculation or misidentification” for civilian aircraft amid heightened tensions between the US and Iran.

Such restrictions are often precautionary in nature to prevent civilian aircraft from being confused for ones engaged in armed conflict.

The FAA said the restrictions were being issued due to heightened military activities and increased political tensions in the Middle East, which present an inadvertent risk to US civil aviation operations.

Following the FAA, India's Directorate General of Civil Aviation advised Indian commercial carriers to avoid Iranian, Iraqi and Persian Gulf airspace.

The Russian aviation agency, Rosaviatsia, also issued an official recommendation for all Russian airlines to avoid flying over Iran, Iraq, the Persian Gulf and the Gulf of Oman “due to existing risks for the safety of international civil flights.”

German airline Lufthansa said it had canceled its flight from Frankfurt to Tehran on Wednesday in light of the current situation.

At least two Kazakh airlines Air Astana and SCAT were considering rerouting or canceling their flights over Iran following the crash of a Ukrainian plane that killed 176 people.

The plane had taken off from Imam Khomeini International Airport in the Iranian capital when a fire struck one of its engines, said Qassem Biniaz, a spokesman for Iran's Road and Transportation Ministry.

Kazakhstan's officials said that Air Astana, the country's flagship carrier, is currently holding a meeting on whether to reroute or ban flights. SCAT, one of the largest airlines in Kazakhstan, told Russia's Interfax news agency that they were also considering rerouting flights.

United Arab Emirates budget airline flydubai said it had canceled a scheduled flight on Wednesday from Dubai to Baghdad, but was continuing flights to Basra and Najaf.

Emirates airline flights between Dubai and Baghdad were canceled.

"The safety of our passengers, crew and aircraft is our number one priority and will not be compromised,” Emirates said in a statement.

Qatar Airways, however, said its flights to Iraq were operating normally.

"The safety of our passengers and employees is of the highest importance, and we continue to closely monitor developments in Iraq,” the airline said in a statement.