ISLAMABAD / RAWALPINDI, Sept 25: Airports across the country were put on full alert on Thursday morning after threats that they could face terrorist attacks.

All 36 airports were placed on a state of ‘red alert’ following an anonymous call that a suicide bomber might target the capital’s Benazir Bhutto Shaheed International Airport.

Officials said security at airports would remain heightened, although the deadline of 12.40pm given in the call had passed.

Most of the airports were already on high alert because of the security situation. The new measures mean that there will be extra vigilance.

Enhanced security measures taken by the Airport Security Force included tighter access rules, search of all hand luggage and ‘100 per cent’ checking of all baggage.

Heavily armed security personnel were stationed at strategic points around the terminals.

Intensified baggage checks and ‘passenger profiling’ of the huge number of people passing through the airports caused chaos at most airports.

However, the level of security varied from one airport to the other.

At Islamabad airport, no chances were being taken.

Officials said only passengers were being let in and no visitors could accompany them. Parking of vehicles was also barred.

“Security personnel have been asked to step up surveillance and only allow passengers with valid tickets to enter the premises,” airport manager Ayaz Jadoon said.

In Lahore, the security measures were less strict.

Kamran Malik, public relations officer at Allama Iqbal International Airport, said visitors had not been affected and car parking was being allowed after thorough search.

Karachi Quaid-i-Azam International Airport also raised its security level, but the measures were less stringent than those in Islamabad.

Flight operations at all airports remained unaffected and there were no delays because of the new security measures, Civil Aviation Authority spokesman Pervez George said. An air force plane started scanning the airfield and security officials were deployed on the rooftop of the building after a caller said a suicide bomber would hit the Islamabad and Karachi airports after 12.20pm.

The airport authorities placed all emergency services on alert and called bomb disposal experts. A search for explosives followed.

A part of the airport complex was closed for some time and public and VIP parking areas were evacuated.

A red alert level means that a terrorist attack is expected, an official said.

Airport Security Force (ASF) personnel were deployed along the runway, all gates were closed and patrolling around the building was stepped up.

Temporary entry passes were cancelled and heavy iron blocks were placed at entry and exit points.

Mr Jadoon said the call was received at around 9.30am.

“We will not remove all the security measures immediately. However, the level will be downgraded after security clearance,” Mr Jadoon said.

AFP adds: Officials said passengers were briefly evacuated from the capital’s airport while security officials searched the area.