Ten militants were among the dead, officials said, as Pakistan's biggest city witnessed a return of the kind of spectacular offensive waged before by the Tehreek-e-Taliban Pakistan (TTP) during an insurgency that has claimed thousands of lives since 2007.

The attack at Karachi's Jinnah International Airport began just before midnight Sunday. At around dawn, the military said that all 10 attackers had been killed.

Some of the gunmen were dressed in army uniform, as authorities put their mangled bodies, assault rifles, grenades and rocket launchers on show for the press. At least three blew up their suicide vests, witnesses said, and one severed head formed part of the grisly display.

But after authorities initially declared the airport cleared around dawn, an AFP reporter witnessed fresh gunfire break out inside the airport -- where explosions and fires had erupted during the night -- prompting security forces to relaunch the operation.

"The attack is over and we have cleared the area of all militants," a spokesman for the paramilitary Rangers, Sibtain Rizvi, told reporters later after nearly 12 hours of fighting in all.

The bodies of the 18 victims of the Taliban assault -- including 11 airport security guards and four workers from Pakistan International Airlines (PIA) -- were taken to a Karachi hospital where another 26 wounded people were being treated, a hospital official said.

After the siege, some 50 Civil Aviation Authority (CAA) and PIA employees who had been trapped inside the building all night were seen leaving. PIA spokesman Mashud Tajwar said no airline passengers were caught up in the incident.

Prime Minister Nawaz Sharif's office issued a statement "commending the bravery" of security forces and saying normal flight operations would resume in the afternoon, while Afghan President Hamid Karzai -- who is battling his own Taliban insurgency -- condemned the attack in a statement.

NJF/NJF