Authorities on Sunday stepped up security at Hyderabad Airport following reported threats to hijack an aircraft.
Security was beefed up at the Rajiv Gandhi International Airport at Shamshabad on the city's outskirts as agencies responsible for different layers of security were put on alert.
Police beefed up the security at the main entry points to the airport area from Bengaluru and Srisailam highways. All vehicles were thoroughly checked.
The Central Industrial Security Force (CISF), which is responsible for the security at the airport, deployed additional personnel in and around the terminal.
It enhanced baggage scanning, pre-embarkation checks and frisking of passengers.
An alert was also sounded at Mumbai and Chennai airports.
This came after a woman sent an email to a senior police officer in Mumbai stating that she overheard six men at a restaurant discussing simultaneous hijack of flights from the three airports.
Officials said while it could be a fake alarm, they were not taking any chances.
The CISF put the security apparatus on enhanced alert. It called sniffer dog squads and quick reaction teams for sanitisation drills.
The security agencies stepped up the vigil in around the terminal and at parking lot. The airlines were asked to be more vigilant.
Airlines have advised passengers to report on time and avoid last-minute check-ins. Passengers have also been advised to cooperate with the security personnel.