Security men at the Rajiv Gandhi International Airport were kept on their toes on Friday, after the Central Industrial Security Force received an anonymous letter claiming that explosives would be transported either on a flight between Hyderabad and Delhi.

The letter did not mention the flight’s name or the time it would arrive at the airport, but warned security personnel to be careful. It also said the consignment would land at the airport within 20 days, police sources said. They, however, ruled out any link to the first anniversary of the Dilsukhnagar twin blasts.

“It’s an anonymous letter written in English. We are trying to get a copy from the airport officials to examine it in detail,” said Cyberabad Joint Commissioner of Police Y. Gangadhar.

As the CISF takes care of security inside the airport, Cyberabad police only focuses on the premises outside the airport. Two check-posts have been established on the main stretches connecting the airport from Shamshabad and Srisailam, he said.

“We are not allowing parking of vehicles in front of the airport and a constant vigil is being maintained on those moving suspiciously,” another police official said.

A few weeks ago, security was tightened at the airport after an alert was sounded, that terrorists could hijack a plane.

More In: Hyderabad