Two Americans suffered minor injuries, but one Pakistani passer-by was killed and at least 10 others were wounded in the attack in the city of Peshawar, officials said. The strike was the first on Westerners since the May 2 raid by American commandos on bin Laden's hideout in an army town around three hours from Peshawar.
The Pakistani Taliban, an Al Qaeda-allied group behind scores of attacks in recent years, claimed responsibility.
"We say to the Americans and NATO that we will carry out more deadly attacks and we can do it," Taliban spokesman Ahsanullah Ahsan said in a phone call from an undisclosed location. "We had warned that we will avenge the martyrdom of Osama."
The Americans were travelling in two cars from their homes to the heavily-protected consulate building when the bomber on a motorbike struck one of the vehicles, said U.S. Embassy spokesman Alberto Rodriguez. The Americans from the hit car were whisked away from the scene in the second vehicle.
The most serious wound was a possible broken hand, he said.
Pakistani police's initial reports contradicted Rodriguez's account by suggesting it was a car bomb, and made no mention of a suicide attacker. But the police were still investigating.
Rodriguez declined to say what job the Americans held. The consulate is home to diplomats, security contractors and - it is widely believed - CIA staff hunting Al Qaeda and associated groups. Both the consulate building and a previous top officer there have been attacked in the past.
The city has witnessed many of the suicide and other bombings that have scarred Pakistan over the past five years, the vast majority against Pakistani government and security force targets. Foreigners in Pakistan have also been targeted, but not nearly as much.
Last week, the Pakistani Taliban killed more than 80 Pakistani recruits for a paramilitary border force in double suicide attacks close to Peshawar. They said those blasts were also in revenge for the death of bin Laden.
Pakistani TV footage showed that the car that was hit was a large, sport utility vehicle. It appeared to have veered into a pole and the hood was damaged. Nearby buildings also were damaged in the blast.
In August 2008, Lynne Tracy, then the top U.S. diplomat at the consulate, survived a gun attack on her armoured vehicle. In April last year, militants used car bombs and grenades to strike the consulate, killing eight people. None of the dead were U.S. citizens, but several were security guards working for the consulate.
The U.S. raid that killed bin Laden in Abbottabad has badly damaged Pakistani-American relations.
Pakistan is angry it was not warned in advance that the Navy SEALs team would storm bin Laden's compound, and insists it had no idea the terror mastermind was hiding there. U.S. officials have visited Pakistan in recent days to try to patch up differences, and assure Pakistan's continued cooperation in the battle against Al Qaeda and allies Islamist militant groups.
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