Sniffer dogs were also deployed during the operation, airport sources said.
Authorities at the Kolkata airport on Monday received a bomb threat by email, three days after a similar communication, triggering a frantic search across the facility, officials said. However, the mail, which threatened to blow up the airport, turned out to be a hoax, they said.
The threat mail was sent to all airports in the country on Monday, said Aishwariya Sagar, the Deputy Commissioner of Police, Airport Division of Bidhannagar Police Commissionerate.
Security agencies at the Netaji Subhas Chandra Bose International Airport (NSCBIA) conducted a thorough search operation after receiving the email, she said.
The CISF conducted the search in the airport's terminal building and operational area, while police personnel carried out checks in the city-side area. Sniffer dogs were also deployed during the operation, airport sources said.
"The security personnel concluded that the threat was a hoax," Ms Sagar said. Efforts were underway to track the sender of the email. A cybercrime case will be started, the sources added.
On April 26, the Kolkata airport authorities had received an email, claiming bombs were planted at various places on its premises. However, the mail turned out to be a hoax, too.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)