Tata Group-owned Air India on Monday said two of its passengers, who were travelling in a San Francisco-Mumbai flight, were relocated after they complained about the presence of 'a few small cockroaches on board'.

The incident happened on Air India flight AI180.

It operates between San Francisco and Mumbai via Kolkata.

In a statement, Air India said: "On flight AI180 from San Francisco to Mumbai via Kolkata, two passengers were unfortunately bothered by the presence of a few small cockroaches on board."

The aviation major said the two passengers were relocated to other seats in the same cabin.

Air India said the passengers remained 'comfortable' thereafter.

Air India said the flight underwent a deep cleaning process after it reached Kolkata.

"The same aircraft subsequently departed in time for Mumbai," the statement said.

"Despite our regular fumigation efforts, insects can sometimes enter an aircraft during ground operations. Air India will be undertaking a comprehensive investigation to determine the source and the cause of this incident and implement measures to prevent recurrence," Air India said.

The Indian aviation goant apologised for 'any inconvenience' caused to the passengers.