Karachi (AFP) - Heavily armed militants attacked Pakistan's busiest airport in the southern city of Karachi Sunday night, forcing the suspension of all flights as the army was called in to repel the gunmen, officials said.
The assault has raised fears about the possibility of a prolonged siege similar to other brazen attacks on key installations in recent years.
Army spokesman Colonel Nayer said that troops had been deployed from the Malir cantonment near their airport. "They have reached the scene," he said.
A spokesman for Airport Security Force (ASF) told AFP: "Four to five terrorists have managed to reach the runway, they are heavily armed with ammunition and grenades and ASF commandos have cordoned off the area along with police and rangers.
"A gun battle is continued between terrorists and forces," he added.
The spokesman said the gunmen had entered the airport by cutting through a barbed-wire fence at the airport's old terminal which is no longer used for passengers but instead has offices, workshops and hangars.
"The old terminal is attached to the runways being used for the new airport's flight operations," he added.
An intelligence official confirmed the ASF's account.
Senior police official Rao Muhammad Anwar had earlier placed the number of attackers at "four to six", while a spokesman for the Civil Aviation Authority added all flights had been suspended.
Television footage showed plumes of smoke rising from the runway and fires where planes were parked. It has not yet been confirmed whether there have been casualties on either side.
There has so far been no claim of responsibility for Sunday night's incident but similar raids in the past have been claimed by Taliban militants who rose up against the Pakistani state in 2007 in an insurgency that has claimed thousands of lives.
Taliban gunmen attacked a Karachi naval base in 2011, destroying two US-made Orion aircraft and killing 10 personnel in a 17-hour siege.
Taliban and other militants in uniform carried out a similar raid at Pakistan's military headquarters in the garrison city of Rawalpindi in 2009, leaving 23 dead.
Prime Minister Nawaz Sharif's government began negotiations with the umbrella militant group Tehreek-e-Taliban Pakistan (TTP) in February, with a ceasefire beginning March 1 but breaking down a month later.
The TTP emerged in response to a raid on a radical mosque in Islamabad, but Islamist violence in the country began to surge in 2004 following the army's deployment in the volatile tribal areas.