ISLAMABAD: Pakistan defended its intelligence agencies Tuesday after a bloody week which saw 125 people killed in a wave of attacks blamed on emboldened Taliban militants holed up in the northwest tribal belt.

Interior Minister Rehman Malik once again vowed to wipe out the Islamist extremist threat to Pakistan, with a fierce military operation into the Taliban's mountain sanctuaries believed to be on the horizon.

The military claims to have already quashed militants in the one-time tourist paradise of Swat valley, but on Monday a suicide bombing struck in the neighbouring northwest district of Shangla, killing 45 people.

A weekend raid and hostage drama at Pakistan's army headquarters meanwhile hit at the heart of one of the most powerful institutions in the nuclear-armed nation.

"Don't blame intelligence agencies, they have foiled several planned attacks, we foiled at least a hundred attacks before they were carried out. Intelligence agencies stand devoted to peace," Malik told reporters.

Local media have reported that the threat to army headquarters in the garrison city of Rawalpindi was known in advance by police, and have questioned why the siege which left 23 people dead was not thwarted.

On October 5, The News published extracts of a letter reportedly sent to the Punjab police by the interior ministry, warning that militants in army uniforms were planning to target the HQ -- exactly what happened days later.

As relayed by the newspaper, the letter said that such an attack was being planned by the Pakistani Taliban, working with banned Sunni Muslim extremist group Lashkar-e-Jhangvi.

The alleged ringleader of the weekend raid, and the only survivor on the 10-member militant team, was a known insurgent with alleged links to a string of attacks.

Security officials have said the arrested militant, named Aqeel and also known as Doctor Usman, was wanted in connection with a March attack on the Sri Lankan cricket team in Lahore which killed eight people.

"Dr Usman is an ex-military official. He is involved in various attacks including the Marriott bombing," Malik said, referring to the September 2008 truck bomb outside the hotel in Islamabad which killed at least 60 people.

Military spokesman Major General Athar Abbas has said the army HQ attack was planned in the Taliban stronghold of South Waziristan on the Afghan border.

The Tehreek-e-Taliban Pakistan (TTP) movement has claimed responsibility for the raid, and threatened more attacks.

The TTP is delivering on a vow of vengeance following the death of its leader Baitullah Mehsud in a US missile strike in Waziristan in August. There was a brief lull in violence as the Taliban leadership regrouped, but the comeback has been fierce.

The upsurge began last Monday, when a suicide bomber walked into the lobby of the Islamabad offices of the UN's World Food Programme, killing four Pakistanis and an Iraqi.

Then on Friday, a massive suicide car bomb exploded at a market in the northwest capital Peshawar, killing at least 52 people in one of the deadliest militant strikes this year.

The latest attack hit Alpuri town in Shangla on Monday, with 39 civilians and six soldiers killed when a boy aged about 13 or 14 flung himself at a military convoy passing through a crowded market.

"The attacker was a young boy. He was standing at the side of the road. As soon as the convoy arrived, he rushed into the vehicles and blew himself up," local administration chief Fazle Karim Khattak told AFP.

The nation is now awaiting a military operation in the semi-autonomous tribal belt, which the government ordered months ago.

Thousands of civilians have fled South Waziristan fearing an imminent offensive, while Pakistani fighter jets have been carrying out air raids in the region and blocking key roads in an attempt to choke off the rebels.

Malik said the military were weighing up the best timing for the operation targeting the TTP leadership.

"They are the enemies of Islam and Pakistan. They are hired assassins and their only aim is to destabilise and defame Pakistan," he said.

"We will defeat them and send them on (the) run."