The audacious attack targeted the army's headquarters

The Taliban say they were responsible for a weekend attack on the military headquarters in northern Pakistan which left at least 19 people dead.

Spokesman Azam Tariq said the attack was carried out by a Punjab faction of the group.

Armed militants ambushed the base in Rawalpindi, near Islamabad, taking hostages before being overpowered.

Azam Tariq said it was to avenge the recent killing of Pakistani Taliban leader Baitullah Mehsud by a US drone.

In a telephone call to news agencies, the spokesman warned of further attacks.

"We will take revenge for our martyrs and will carry out more attacks, whether it's the GHQ [the army's general headquarters] or something bigger," he was quoted as telling Reuters.

In the wake of the assault, Pakistan's Interior Minister Rehman Malik said the military would "imminently" launch an operation in South Waziristan, site of strongholds of the Taliban and al-Qaeda.

On Monday, more than 20 people were killed in a bombing near Swat valley in north-west Pakistan.

The explosion hit a security convoy in Shangla district - an area the military said it had retaken from the militants.

Punjab link

Six soldiers and four militants died in the initial assault on the army HQ on Saturday, in one of the seemingly most secure parts of the country.

The remaining attackers took dozens of hostages inside the facility before commandos stormed the building a day later. One insurgent, named by police as Aqeel, or Dr Usman, was captured alive.

On Monday a case against him was officially registered by police.

Local media reports say that he was a resident of a village near Kahuta in Rawalpindi district.

Analysts say his arrest points to the increasing involvement of insurgents based in the Punjab district in militancy across the north-west.

Taliban militants have traditionally been recruited from Pakistan's volatile north-western tribal regions.

After Baitullah Mehsud was killed by a US missile in early August, there was a relative lull in Taliban attacks.

But the last few weeks has seen a resurgence in militant activity.