Air India said Tuesday an investigation was underway after a passenger found worms in his sandwich mid-flight.
The passenger made the discovery during a flight from New York to New Delhi on September 28 on India's struggling flagship carrier.
The passenger reported the incident to Air India, but said he did not hear anything back for two weeks, according to the Press Trust of India.
"We are investigating the caterer regarding this incident," airline spokesman Prasad Rao said in New Delhi.
The spokesman said the airline maintained high standards, including hygiene conditions, adding that this was a "very rare incident".
The loss-making airline has been hit by a string of issues, including over safety. In May, a flight to Bangalore was diverted to another city after the pilot returned from a toilet break and found the door to the cockpit jammed shut.
Air India also this year suspended a senior pilot caught drunk just before he was to fly a passenger aircraft.
Air India is the country's fourth-largest airline by market share, and has been hit hard by rising fuel prices and fierce competition from private carriers that have added to a legacy of labour problems and crushing debts.
Meanwhile, a family of live rats has been found in the business class cabin of a plane at Xiamen Airport. The flight had come from Hong Kong.
Inspectors found 10 rat pups under a business class seat and immediately closed the cabin for an inspection. The mother rat was found the following day.
Authorities said it was the largest number of live rats they had ever found on a plane. The plane was later given the all-clear after confirming its wiring was intact.