A powerful suicide car bomb ripped through the Peshawar headquarters of Pakistan's top spy agency Friday, killing at least 10 people and leaving much of the fortified building in ruins.
A similar bombing killed eight people in another northwest town, the latest in a spate of attacks as 30,000 troops press their most ambitious assault yet against Taliban militants in their mountain strongholds on the Afghan border.
The attack devastated the three-storey Inter Services Intelligence (ISI) provincial headquarters in the northwestern city of Peshawar, sending huge clouds of smoke spewing into the sky and destroying more than half of the building.
The bomber, driving a mini-truck loaded with explosives, raced down the road towards the ISI building shortly before sunrise, provincial information minister Mian Iftikhar Hussain said.
Soldiers opened fire after they spotted the truck, but the bomber ploughed into a steel barrier and blew up the vehicle outside the main gate of the ISI compound, wreaking massive destruction, he added.
More than half of the U-shaped building was destroyed by the force of the blast which devastated its outer wall, a front portion and a column, and scattered bodies among the rubble, an AFP reporter said.
Peshawar, on the edge of Pakistan's lawless tribal belt infested with Al-Qaeda and Taliban fighters, has increasingly become the favoured target for major attacks by suspected Taliban militants in recent months, particularly since the army launched its massive offensive in October.
Absar Ahmed, a 25-year-old taxi driver, said he was driving near the ISI building when he heard gunshots followed by a huge blast.
"My car was hurled on to the pavement by the force of the blast and my head banged into the windscreen. When I looked back to check on my passenger there was smoke all over," Ahmed told AFP in hospital.
The attacks coincided with a visit by US National Security Advisor James Jones who held talks with Pakistan's army chief, General Ashfaq Kayani.
The United States has put Pakistan on the frontline of its war against Al-Qaeda and has been increasingly disturbed by deteriorating security in the country where attacks and bombings have killed about 2,500 people in 28 months.
Pakistan's powerful and shadowy intelligence agencies have a history of supporting the Islamist groups in a bid to counter rival India, but militant attacks have turned against domestic security targets in the last two years.
"Seven military officials and three civilians were martyred and 60 others were injured," a military statement said.
"Up to 300 kilograms (660 pounds) of high explosives and mortars were packed into the car bomb," provincial police chief Malik Naveed told AFP.
A second suicide bomber rammed a car packed with explosives into a suburban police station in the garrison town of Bannu, southwest of Peshawar, killing seven security personnel and a prisoner, police said.
The most devastating bomb attack in Pakistan in two years killed at least 118 people in a crowded Peshawar market on October 28 as militants put ordinary civilians in the crosshairs of their bloody campaign.
Friday's bombing was the first major attack outside an ISI installation since May, when a suicide attack on a police building in the city of Lahore killed 24 people.
The government blames increasing attacks on Tehreek-e-Taliban Pakistan (TTP), which is the target of the ongoing offensive and which wants to avenge the killing of their leader Baitullah Mehsud by a US missile in August.
The latest attacks came after stiff Taliban resistance killed at least 17 Pakistani soldiers Thursday in the military's deadliest day since launching its major offensive in South Waziristan, security officials said.
Pakistan has sent a 30,000-strong force, backed by war planes and attack helicopters, into battle in a US-endorsed mission to wipe out the chief strongholds of Tehreek-e-Taliban in the tribal district of South Waziristan.
Lieutenant General Nadeem Ahmed, who heads up relief efforts for the displaced, said the "active" operation would "be over within days" and the army will consolidate its positions, allowing refugees to return in the spring.
Near the southwestern border with Afghanistan, suspected Taliban militants torched five trucks carrying fuel to NATO forces there, police said.