RAWALPINDI, June 1: Pakistan Air Force (PAF) Chaklala Airbase and Benazir Bhutto International Airport were put on high alert on Tuesday night after an intelligence agency warned that terrorists might target them, official sources said here on Wednesday.

A senior police official also confirmed that high alert was declared in the wake of a tip-off from an intelligence agency that terrorists might strike at the PAF Airbase some time on Tuesday night.

He added: “The security clampdown came as the intelligence sounded a severe warning to the authorities concerned to remain vigilant at the airport.”

Security around sensitive government installations and foreign missions had already been stepped up across the country after the killing of Osama bin Laden by US forces in Abbottabad and terrorist attack on the PNS Mehran in Karachi.

According to the sources, the police had already intimated to the authorities at the PAF base that three major 'loopholes' in the security of the base had been spotted that might be used by terrorists.

The senior police official said: “Yes, the police had intimated the authorities concerned about the 'loopholes' in the security at the PAF base and on the other sides of the runways and expressed concern over taking the security issue lightly.” However, he refused to give details.

On Tuesday night, immediately after the threat was received, the Elite Force commandoes, local police, military police and intelligence officials were deployed at the PAF base Chaklala in addition to launching police patrolling and surveillance in the sensitive areas.

The senior police official requesting not to be named said: “The security alert remained till Wednesday morning to ensure that the airport and other important installations were safe. However, nobody was arrested.”

As part of the security clampdown, the police were stopping motorists and searching cars on roads that run beneath the airport's flight path and keeping a vigil on passersby.

Though the use of military police to assist the local police and Elite Force commandoes was not unusual, motorists and passersby were stunned on seeing the presence of such a large number of police and elite commandoes along with the military police.

As part of the tightened security, a 'hydraulic road blocker', which is designed to prevent unauthorised vehicles from entering the building, has been installed at the strictly guarded and controlled entrance of the Airport Security Force (ASF) camp located in the western side of the airport.