He continued: “They are moving back, we are trying to nab them,” adding that no security forces had so far been hurt or killed.

Another security official at the scene told reporters that the attack involved around 10 militants.

Flights were suspended once more, having resumed following the previous attack.

“We have suspended all flight operations at Karachi airport and we are evacuating passengers,” said Mashud Tajwar, a spokesman for Pakistan International Airlines.

Civil Aviation Authority spokesman Abid Qaimkhani added that incoming flights had been diverted.

The checkpost is located at the entrance of an ASF camp some 500 metres away from the main airport premises, or one kilometre from the passenger terminal.

A reporter at the scene said rangers, police and army commandos were arriving at the camp, which has little by way of cover and were taking up positions to engage the militants in an open field.

The assault came as Pakistan launched air strikes on a militant-infested tribal district, killing 15 people in apparent retaliation for Monday’s assault.

Ten Taliban fighters, some dressed in military uniform and armed with machine guns, grenades and rocket launchers launched the attack on Sunday night.

Their main objective “was to destroy the aircraft on the ground but there was only minor damage to two to three aircraft,” Interior Minister Chaudhry Nisar Ali Khan said late on Monday.

The Taliban had vowed the first attack was just the beginning as they sought to avenge the death of their former chief Hakimullah Mehsud.