A Mumbai-bound Air India Boeing 777 aircraft was forced to return to Delhi on Monday morning due to a technical issue with its right engine, sources said. The flight, carrying around 335 passengers and crew, had been airborne for nearly an hour before making an emergency landing.

"The crew operating flight AI887 from Delhi to Mumbai on 22 December decided to return to Delhi shortly after take-off due to a technical issue as per standard operating procedure," Air India said in a statement.

The airline confirmed that the aircraft landed safely and all passengers and crew have disembarked. It added that it “regretted the inconvenience caused due to this unforeseen situation.”

A source at the Directorate General of Civil Aviation (DGCA) explained the reason for the emergency return: during flap retraction after take-off, the flight crew observed low engine oil pressure on the right-hand engine.

"The engine oil pressure dropped to zero, and the inspection is in progress," the source said.

The source further noted that a review of previous records did not indicate any abnormality in oil consumption.

Air India stated that the plane is currently undergoing necessary checks and that alternative arrangements have been made to fly the passengers to Mumbai.

Flight AI887, operated with a Boeing 777-300 ER aircraft, had taken off around 6:30 am and remained airborne for about an hour, according to data from flight tracking website Flightradar24.com.