All airports operating flights to and from Nepal have been put on an alert in the wake of an intelligence tipoff about possible attempts by Maoist rebels in the Himalayan kingdom to hijack an Indian aircraft, official sources said on Tuesday.

The alert follows an input received by the Central Industrial Security Force, manning security at Indian airports, from the Bureau of Civil Aviation, they said.

"The airports have been asked to streamline security to prevent any attempt to hijack a plane," the sources said.

The CISF has also conveyed the intelligence input to other airlines operating in the India-Nepal circuit.

A senior Intelligence Bureau official in Delhi told rediff.com that Maoists are not known to possess the expertise to hijack an aircraft but then, it is no reason to be complacent. Hence, security personnel have been put on alert.