Kolkata: A bomb threat written on the washroom mirror of an IndiGo flight from Thailand's Phuket to Kolkata resulted in an extensive security check on Saturday, leaving passengers stranded on the airport tarmac for nearly two hours after landing, airport officials said.

The flight 6E1494, which was carrying around 8.80 per cent of its passenger capacity, landed at Kolkata's Netaji Subhas Chandra Bose International (NSCBI) Airport at 2:05 p.m.

Shortly after landing, the cabin crew spotted the threatening message written on the mirror inside the aircraft's toilet.

Soon after the discovery, passengers were evacuated from the aircraft and made to wait on the tarmac while the plane was moved to an isolation bay for a thorough security check.

The search continued for more than two hours, with passengers allowed to enter the airport terminal only around 4:30 p.m., once the security checks concluded.

"The matter was immediately reported to the pilot and airport security officials. Within moments, the plane was taken to the isolation bay. The passengers were safely de-boarded and a search was started by CISF, Bomb Squad and Airport Police. However, despite a long search, nothing suspicious was recovered from inside the plane. Initial speculation is that someone did this to spread panic," an official said.

Police are examining the passenger list and CCTV footage of the plane to find out who wrote the note.

The development came a day after a bomb threat, written on a tissue paper, was found at the Netaji Subhash Chandra Bose International Airport.

On Friday, the cleaning staff reportedly found a handwritten note in the women's restroom within the airport, warning that a bomb had been planted at Gate Number 30.

According to sources aware of the development, the workers panicked after seeing the note, written on tissue paper, and immediately brought the matter to the notice of the higher officials.

Security personnel quickly cleared the crowd from that particular entrance, and a search operation was conducted there by the bomb squad and the CISF personnel, as well as elsewhere within the airport premises.

However, nothing suspicious had been found so far by the CISF troopers and personnel of the Airport Police Station, which comes under the jurisdiction of the Bidhannagar City Police in North 24 Parganas district.