Sky marshals are deployed on select routes perceived to be prone to terrorism,' Indian Airlines Deputy Managing Director V Kashyap told rediff.com on Saturday while talking about the 'hijack' of an Alliance Air aircraft (a subsidiary of IA). The 'hijack' turned out to be a mock drill by security agencies.

He said National Security Guard commandos are deployed on select Indian Airlines flights after consultations with the security agencies concerned.

"The threat of terrorism is felt all over the world. We are taking all measures to ensure that passengers and aircraft are safe," he said.

NSG commandos are given special training on aviation security after which they are deployed as sky marshals, who mingle among passengers in civilian dress, IA sources told rediff.com.

Private airlines like Jet Airways and Sahara earlier resisted having sky marshals, but later saw the usefulness in having them, sources said.

Kashyap acknowledged that sky marshals were deployed on private airlines.

The sources indicated that certain international guidelines had been issued for aviation security but the details could not be divulged.