United Airlines has suspended its Newark-Mumbai service as the US issued a ban on flights over parts of Iran-controlled airspace.

The warning of heightened military activities and increased political tensions followed the shooting down of a US surveillance drone on Wednesday over the Gulf of Oman.

The US blamed Tehran for the incident and now says tensions in the region present a risk to US civil aviation. Iran said the drone had violated Iranian airspace, but the US military denied this.

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United withdrew flights from Newark to the Indian financial capital, which operate through Iranian airspace, following a “thorough safety and security review”.

A spokesman told Reuters: “We continue to explore all our options and remain in close contact with relevant government authorities in order to provide our customers with the most efficient travel experience under these circumstances.”

American Airlines and Delta Air Lines said they did not fly over Iran.

The FAA said the nearest civil aircraft was operating within around 45 nautical miles of a US Global Hawk drone when it was shot down by an Iranian surface-to-air missile, according to flight tracking applications.

“There were numerous civil aviation aircraft operating in the area at the time of the intercept,” the FAA said.

More: FCO advises British-Iranians against travelling to Iran