Thiruvananthapuram | Thiruvananthapuram international airport was placed on high alert on Thursday morning after a bomb threat message was found on an Air India flight from Mumbai, prompting an extensive security check of the plane before the emergency was later withdrawn.

The emergency status was withdrawn at around 12.10 pm, according to airport sources who declined to confirm whether the threat was a hoax.

Police officers from the Valiyathura police station arrived at the airport to investigate the incident.

Earlier in the morning, the pilot of the aircraft informed the ATC about the threat after a 'Bomb in flight' message, written on a tissue paper, was found in the washroom of the plane, the sources said.

The bomb threat was communicated by the pilot at 7.30 am as the aircraft approached the Thiruvananthapuram airport, the sources said.

Subsequently, a full emergency was declared at the airport at 7.36 am, they said.

Thereafter, the aircraft with 135 passengers on-board landed safely at the airport around 8 am and was moved to an isolation bay.

The passengers were evacuated by around 8.44 am and security agencies, including a bomb detection squad, inspected the aircraft for any explosive devices, the sources said.

As a result, the passengers waited at the airport for their luggage to be delivered, they said.

Meanwhile, Air India, in a statement, said that a specific security alert was detected on flight AI 657 during cruise from Mumbai to Thiruvananthapuram and "the crew carried out all the laid down security drills keeping passenger safety as top priority." "All passengers and crew disembarked safely. Air India accords top priority to the safety of its passengers and crew," an airline spokesperson said.

"There has been no impact on life. Airport operations are currently uninterrupted," the airport sources said.