Canada’s transport regulator has asked Air India to investigate an incident of a pilot reporting for duty under the influence of alcohol and failing two breathalyser tests, a person familiar with the matter said.

The tests were conducted by Canadian police at Vancouver International Airport, after the pilot was asked to leave the aircraft, the person said.

The incident was labelled as a “serious matter” by Transport Canada in a letter to Air India, and authorities are likely to pursue enforcement action, the person added.

The person requested anonymity as he was not authorised to speak to the media. Transport Canada did not respond to an emailed request for comment outside regular working hours.

In a statement, Air India confirmed the flight from Vancouver to Delhi on December 23 experienced a last-minute delay due to the incident, adding that an alternate pilot was brought in to operate the flight.

“The pilot has been taken off flying duties during the process of enquiry. Air India maintains a zero-tolerance policy towards any violation of applicable rules and regulations,” Air India said.

“Pending the outcome of the investigation, any confirmed violation will attract strict disciplinary action in line with company policy.”

The letter from Transport Canada official Ajit Oommen has asked Air India to provide its findings and details of steps taken to prevent future occurrences by January 26, the person familiar with the matter said.

India has been under intense scrutiny since the June 12 crash of a Boeing Dreamliner killed 260 people. India’s aviation regulator has flagged multiple safety lapses at the airline, which was previously owned by the government until 2022.

Pilots at Air India, owned by Tata Group and Singapore Airlines, have also come under scrutiny.

This week, India’s Directorate General of Civil Aviation sent warning notices to four Air India pilots, flagging “serious safety concerns” related to regulatory compliance and flight crew decision-making.

The DGCA said the pilots accepted an aircraft for operation last year despite prior knowledge of “repeated snags” and “existing systems degradations,” according to warning notices dated December 29 seen by Reuters.

The aircraft is a Boeing 787 used for long-haul flights, according to Flightradar24.