A second attack on Pakistan's Karachi airport in as many days has ended, a spokesman for the Airport Security Force said, adding that the two gunmen involved had escaped.

The Taliban have claimed responsibility for the raid a day after a siege by the militant group on the airport left 37 dead, according to Reuters.

"It was not such a big attack, two people came towards the ASF checkpost and started firing," Colonel Tahir Ali told reporters.

"They ran away after the firing and because we are on high alert, under the standard operating procedure we called in [paramilitary] rangers and the army."

The latest attack raises further questions about authorities' ability to secure key facilities in the face of a seemingly resurgent enemy, as a nascent peace process with the Pakistani Taliban lies in tatters.

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 checkpoint is located at the entrance of an ASF camp some 500 metres away from the main airport premises, or 1km from the passenger terminal.

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 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.

Earlier today, charred bodies of seven Karachi airport workers who phoned their families as they hid in a cold-storage facility that was engulfed in flames during Monday's attack, were recovered by Pakistani authorities.

The victims' families had staged a protest on a main road in Karachi last night demanding authorities find their relatives, saying they had been in contact via telephone during the attack.