AKIPRESS.COM - Pakistan's army says it has launched a "comprehensive operation" against militants in North Waziristan, near the Afghan border.

It comes hours after fighter jets carried out air strikes against militant strongholds in the area.

Officials said scores of insurgents were killed in the air raids but this has not been independently confirmed.

Among them was a suspected Uzbek leader of the deadly attack on Karachi airport a week ago, they added.

At least 28 people were killed in the airport attack, as well as all 10 gunmen.

The BBC's Mike Wooldridge in Islamabad says a large-scale military offensive in North Waziristan has long been mooted and air strikes in the region have intensified since the attack on Karachi.

It is not clear how many ground troops will be involved, he adds, but military experts warn it will be a complex and challenging operation.

The US has long pressed for such an operation in North Waziristan, one of the last areas in the restive north-west where a large-scale push against insurgents has not taken place.

"On the directions of the government, armed forces of Pakistan have launched a comprehensive operation against foreign and local terrorists who are hiding in sanctuaries in North Waziristan," a military statement said.

The army later said troops had encircled militant bases in the towns of Mirali and Miranshah but it was unclear if fighting was under way. Afghan security forces have been asked to to seal the border on their side, officials said.

The operation is said to involve the air force, artillery, tanks and ground troops.