Since the closure of Pakistan's airspace on 27 February, many flights have had to be re-rerouted through the Mumbai area, leading to a large increase in air traffic.
The incident happened at 1:40 PM local time, when an Air France Boeing 777, en route From Ho Chi Minh to Paris, had a near-miss with an Airbus A320 on its way from Abu Dhabi to Kathmandu.
"At 1.40 pm, Mumbai air traffic control (ATC) asked the Etihad flight to climb to 33,000 feet. During climb, this aircraft came almost face-to-face with an AF 253 coming from the opposite direction. The two aircraft were just three nautical miles away, and seconds apart, from each other," said sources, as quoted by the India Times.
According to the Directorate General of Civil Aviation, an investigation into the incident has been started.
Meanwhile, Pakistan announced last week that it could partially open its airspace, but at the moment the only flights allowed are those offering service to Pakistani cities.