A combination of "pungent" and "burning smell" inside an Air India Express flight forced about 175 passengers bound for Sharjah to return after takeoff from here. The culprit -- possibly a box of onions in the cargo hold area of the flight.

At first, one of the passengers on the Sharjah-bound Air India Express flight (IX 411) that took off from here on August 2 night, complained of a smell of something "burning" inside the flight, an airline source said.

Later, some more passengers joined and said there was some "pungent smell" in the flight that had just taken off, forcing a turn around and making a precautionary landing at the Cochin International Airport (CIAL) here.

The engineering team inspected the aircraft, and initial findings showed no evidence of smoke or technical issues, the airline source said.

"The preliminary feedback suggests that the source of the odour may have been attributed to the presence of onions or vegetables being carried in the aircraft", the source said.

As somebody had reported a bad smell inside the aircraft, as a precautionary measure, it was decided to turn back, the source added.

Congress MLA Mathew Kuzhalnadan, who was travelling in the aircraft, said there was uncertainty and confusion among the passengers, but it landed safely.

"To be honest, I fell asleep as soon as I boarded. However, when I woke up with the announcement, there was an uncertainty and confusion among the people. When the captain announced we are landing back then, everyone got concerned and slightly nervous. However, it didn't get worse as we landed back soon," the Muvattupuzha MLA, who is on a private visit to Sharjah, told PTI.

The Air India Express expressed regret for the inconvenience caused and made arrangements for guests on another aircraft, which departed at 5.14 am.

The airline source said the odour might have emanated from the onions or vegetables kept in the airline's cargo hold area.

The Middle East-bound Air India Express airline carries vegetables, fruits, and flowers in large quantities in its cargo hold area, which is also a source of income for it.

"We not only carry passengers, we also carry the produce from our farmers, particularly to the Gulf countries," the source told PTI.

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