KABUL A suicide car bomber killed nine people in an attack on a military airport in eastern Afghanistan on Monday, officials said, the latest bloodshed since copies of the Koran were burned at a NATO base last week.
There was no official indication the explosion at the gates of Jalalabad airport was linked to the deadly protests, but the Taliban claimed responsibility for the attack as "revenge" for the Koran burnings.
Nineteen Afghan civilians and law enforcement officers and four NATO soldiers were wounded in the blast, a spokesman for the NATO-led International Security Assistance Force (ISAF) in Nangarhar province, of which Jalalabad is the capital, said.
Jalalabad airport is almost exclusively used by NATO and the U.S. military.
Anti-Western fury has deepened significantly since the desecration of the Muslim holy book at the main NATO Bagram air base in Afghanistan. NATO described the incident as a tragic blunder.
The U.S. Embassy warned of a "heightened" threat to American citizens in Afghanistan and many Westerners are on "lock down", meaning they are not allowed out of their fortified compounds.
Riots have raged across Afghanistan over the past week despite widespread apologies from U.S. leaders, including President Barack Obama and military commanders.
Seven U.S. military trainers were wounded on Sunday when a grenade was thrown at their base in Afghanistan's north.
Chants of "Death to America!" have come to characterize the protests and some demonstrators have hoisted the white Taliban flag.
With few signs of the crisis abating, the U.S. ambassador said the United States should resist the urge to pull troops out of Afghanistan ahead of schedule.
"Tensions are running very high here. I think we need to let things calm down, return to a more normal atmosphere, and then get on with business," Ambassador Ryan Crocker told CNN.
"This is not the time to decide that we are done here. We have got to redouble our efforts. We've got to create a situation that al Qaeda is not coming back," he said.
Under an international agreement, foreign combat forces are due to leave Afghanistan by the end of 2014, a process which is already under way.
The groundswell of anger over the burning of the Koran, which Muslims revere as the literal word of God, has highlighted the challenges ahead as Western forces try to quell violence and bring about some form of reconciliation with the Taliban.
The violence has killed more than 30 people and wounded at least 200, including two U.S. troops shot dead by an Afghan soldier who joined rallies in the east. Two U.S. officers were also shot at close range inside the Interior Ministry.
In an interview from Rabat, U.S. Secretary of State Hillary Clinton said the violence was "out of hand and it needs to stop".
The shooting of two U.S. officers deep inside the heavily fortified Interior Ministry on Saturday has intensified the sense of unease among Westerners and deepened the divide with their Afghan counterparts.
The attack illustrates the dilemma faced by NATO forces as they move away from a combat role to an advise-and-assist mission, which will require them to place more staff in ministries.
With the 2014 timetable unfolding, pressure is growing for an earlier pullout, especially among Washington's allies in Europe, where the bloody and expensive war is deeply unpopular.
The high-level killings prompted NATO, Britain, Germany and Canada to withdraw their staff from Afghan ministries.
The Taliban also took responsibility for the Interior Ministry attack, although the Islamist group often exaggerates claims involving attacks against Western forces.
On Sunday, the ministry said one of its employees was a suspect in the shooting of the two U.S. officers. Afghan security sources also identified a 25-year-old police intelligence officer as a suspect.
Afghan President Hamid Karzai has repeatedly urged calm and restraint, although he also maintains that those who burned the Korans must be prosecuted.
Similar desecration of the Koran in the past have also sparked violence, although not as widespread and persistent as the riots and protests over the past week.
Last April, seven foreign U.N. staff were killed when protesters overran a base in the northern city of Mazar-i-Sharif after an obscure pastor from a fringe church in the United States deliberately burned a copy of the Koran.
(Additional reporting by Mirwais Harooni in KABUL, Fraidoon Elhaam in KUNDUZ, Rafiq Sherzad in Jalalabad, and Jackie Frank in WASHINGTON; Editing by Michael Georgy and Nick Macfie)