A suicide car bomber rammed his vehicle into the gates of a NATO base and airport in eastern Afghanistan on Monday, triggering a blast that killed nine Afghans, officials said. The Taliban claimed the attack was revenge for U.S. troops burning copies of the Koran.

The bombing in the city of Jalalabad follows six days of deadly protests in the country over the disposal of Korans and other Islamic texts in a burn pit last week at a U.S. military base north of Kabul.

American officials have called the disposal of the books a mistake and have issued a series of apologies. Afghan President Hamid Karzai has urged calm, calling on his countrymen not to allow insurgents to capitalize on their indignation to spark violence.

About 40 people have been killed in protests and related attacks since the incident became known this past Tuesday, including four U.S. soldiers. NATO, France, Britain and the U.S. have pulled their advisers from Afghan ministries out of concern that the anti-foreigner anger might erupt again.

On Monday, the United Nations also scaled back its operations, moving its international staff from an office in the northern city of Kunduz that was attacked during protests Saturday, the organization said in a statement.

The evacuation was ordered "to put in place additional arrangements and measures to make sure the office can continue to operate in safety," the U.N. said, adding that the move is temporary and that staff will be relocated within Afghanistan.

Despite the pullback, the commander of NATO and U.S. forces in Afghanistan said that the partnership with the Afghan government was as strong as ever.

"We are steadfast in our desire to support our Afghan partners, and will use the extensive range of our resources to eradicate this heartless insurgency," Gen. John Allen said in a statement condemning the Jalalabad bombing.

In Monday's attack, the bomber drove up to the gates of the airport, which primarily serves international military aircraft, and detonated his explosives in a "very strong" blast shortly after daybreak, said Nangarhar provincial police spokesman Hazrad Mohammad.

Among the dead were six civilians, two airport guards and one soldier, Mohammad said. Another six people were wounded, he said. An AP photographer saw at least four mangled, charred cars at the site destroyed in the blast.

NATO forces spokesman Capt. Justin Brockhoff said that no international forces were killed in the attack and that the base was not breached by the blast.

The Taliban claimed responsibility for the attack, saying a suicide car bomber had driven up to the airport gate and detonated his explosives as international forces were changing from night to morning guard duty.

"This attack is revenge against those soldiers who burned our Koran," Taliban spokesman Zabiullah Mujahid said in an email.

Afghan officials, including the defense and interior ministers, canceled planned visits to Washington this coming week so they could remain in Kabul for consultations about how to quell the violence, U.S. officials said.

In the highest-profile attack, two military advisers were found dead in their office at the Interior Ministry Saturday in the heart of the capital with shots to the back of their heads.

The incident prompted NATO, Britain and France to recall hundreds of international advisers from Afghan ministries. The advisers are key to helping improve governance and preparing the country's security forces to take on more responsibility ahead of the drawdown of Western forces planned for 2014.

The U.S. had already pulled its advisers from Afghan government offices. The Canadian government also canceled all meetings in Afghan ministries, according to a spokesman.

Police were still searching Monday for the suspect — an Afghan man who worked as a driver for an office on the same floor as the advisers who were killed, said an official at the Interior Ministry who spoke anonymously to discuss ongoing operations. Eight shots were fired at the men — two at the first victim and eight at the second, the official said.

The Taliban claimed that the shooter was one of their sympathizers and that an accomplice had helped him get into the compound to kill the Americans in retaliation for the Koran burnings.

The Taliban also claimed Monday that they had poisoned soldiers at a U.S. base in the east by recruiting a cook who worked there. NATO rejected the report.

"No one got sick," said Lt. Col. Chad Carroll, a spokesman for international forces in the east. He said that a dining facility worker told his superiors that food might have been tampered with, and when they ran tests they found "traces of bleach in a couple of foods."

"We do not know if this was intentional, if it was what the local worker was referring to, or whether it was simply spillage from cleaning," Carroll said.