The Pakistani Taliban has claimed responsibility for an attack on the US consulate in Peshawar in Pakistan's northwest.
The assault was just one of a series of attacks to hit the volatile region on Monday.
As many as 44 people were killed in a blast at a rally in Lower Dir district, while the Peshawar attack - which occurred just hours later - claimed at least six lives.
More than 100 people were wounded in the day's attacks.
"Americans are our enemies," Azam Tariq, a Taliban spokesman, said. "We carried out the attack on their consulate in Peshawar. We plan more such attacks."
No Americans were hurt in the attack, but at least two security personnel and four of the attackers were killed.
The US reaction was swift. "We strongly condemn the violence and the actions," Robert Gibbs, the White House spokesmen, said.
"And I would point out that ... extremists in Pakistan have succeeded in killing Pakistanis, which I think hardens the view that has led to gains that have been made over the course of the year against extremism by native Pakistanis."
The assault on the heavily guarded US consulate in Peshawar involved men armed with guns and grenades and two car bombs.
The security barrier near the consulate gate was damaged, and shells from rocket-propelled grenades and hand grenades were left lying in the area, which was sealed off by Pakistani police and army, witnesses said.
Police said of the two car bombs, one exploded at a checkpoint 50 metres from the consulate while the other - laden with about 100kg of explosives - went off close to the consulate gate.
At least three blasts were reported and a firefight between security forces and the attackers followed.
Pakistani television showed security forces firing their weapons and clouds of smoke rising over the garrison area of the city, close to the Peshawar offices of Pakistan's intelligence agency, which was bombed last November.
Zafar Jaspal, a security analyst in Islamabad, told Al Jazeera that while the government has routed the Taliban from their bases in places like South Waziristan, they are spreading into settled areas.
"The American consulate is one of the most well guarded places in Peshawar," he said.
"It [the attack] was well planned and they very confidently hit their target."
Lower Dir attack
The day's first bombing struck a political rally in the town of Timargarah in Lower Dir.
Zahid Khan, a spokesman for the Awami National Party, said that members of his party had been celebrating plans to change the name of North West Frontier Province, where Lower Dir is located, when a suspected suicide bomber detonated his explosives.
Al Jazeera's Kamal Hyder, reporting from Islamabad, said: "The attacks in Peshawar were well co-ordinated, shook the entire city, yet did not cause the kind of mayhem that we saw in Dir. That will be the only consolation for the security agencies."
The attacks underscore the fact that, despite efforts by the Pakistani government and suspected US drone attacks, the Taliban in Pakistan remains a serious threat.
"Although they have been driven out of their strongholds in key areas, there is a feeling that a substantial number of those people have now infiltrated into the settled areas," our correspondent said.
"There is trouble in the southern parts of the Punjab - so you do see some sort of regrouping attempt and a fear that there maybe an escalation of this sort of violence."
Monday's attacks took place against a backdrop of continuing political tensions in the country.
Addressing a joint session of the two-chamber parliament in Islamabad on Monday, Asif Ali Zardari, Pakistan's president, said: "Militancy and extremism have been the greatest threat to our national security in recent times. I assure you we will fight militancy to the finish."
But in a move that should go some way to silencing his critics, Zardari urged parliament to approve quickly constitutional amendments that will see him give up his main powers.
The amendments include the transfer to the prime minister of the presidential power to dismiss parliament, appoint military chiefs, judges and the election commissioner.
Many had assumed Zardari would never agree to the changes.