A teenage suicide bomber blew himself up outside NATO headquarters in the Afghan capital on Saturday, killing six civilians in a strike that targeted the heart of the U.S.-led military operation in the country, officials said.

The Taliban claimed responsibility for the blast, which was the latest in a series of attacks carried out by insurgents in the heavily-fortified Afghan capital. The U.S.-led coalition launched a campaign this spring aimed at shoring up security in Kabul before a significant withdrawal of combat troops limits American options. The strategy is part of an overall plan to gradually hand over security to Afghan security forces.

While bombings and shootings elsewhere in Afghanistan receive relatively little attention, attacks in the capital score propaganda points for the insurgents by throwing doubt on the government's ability to provide security even the seat of its power. The attacks also aim to undermine coalition claims of progress ahead of the planned withdrawal of foreign troops by the end of 2014.

The bomber struck before noon outside the headquarters of the U.S.-led NATO coalition, on a street that connects the alliance headquarters to the nearby U.S. Embassy, the Italian Embassy, a large U.S. military base, and the Afghan Defense Ministry.

The alliance and police said all the victims were Afghans, and the Ministry of Interior said some were street children. Kabul police said in a statement that the bomber was 14 years old.

The Taliban claimed responsibility for the attack, saying the target was a U.S. intelligence facility nearby.

Jamie Graybeal, a spokesman for the U.S.-led international military alliance, said all coalition compounds in Kabul were currently secure. He said he was not aware of any casualties among members of the coalition.

Interior Ministry spokesman Sediq Sediqi blamed the attack on the Haqqani network, one of the most dangerous militant groups fighting U.S.-led forces in Afghanistan. He did not say what he was basing that conclusion on, but the Haqqani group, which is linked to both the Taliban and al-Qaida, has been responsible for several high-profile attacks in the Afghan capital in the past.

On Friday, the U.S. designated the Pakistan-based Haqqani network a terrorist organization, a move that bans Americans from doing business with members of the group and blocks any assets it holds in the United States.

The Obama administration went forward with the decision despite misgivings about how the largely symbolic act could further stall planned Afghan peace talks or put yet another chill on the United States' already fragile counterterrorism alliance with Pakistan.

The Haqqani network has been blamed for a series of high profile attacks against foreign targets in Kabul, including coordinated attacks last April against NATO and government facilities that lasted more than a day before the insurgents were killed. A year ago, they were blamed for a rocket-propelled grenade assault on the U.S. Embassy and NATO headquarters. In June, gunmen stormed a lakeside hotel near Kabul and 18 people in a 12-hour rampage.

American officials estimate the Haqqani forces at 2,000 to 4,000 fighters and say the group maintains close ties with al-Qaida.

Earlier Saturday, hundreds of Afghans and officials had gathered just a few hundred meters (yards) from the site of the attack to lay wreaths at a statue to commemorate the 11th anniversary of the death of Ahmad Shah Massoud, the charismatic Northern Alliance commander who was killed in an al-Qaida suicide bombing two days before the Sept. 11, 2001, attacks. The alliance joined with the United States to help rout the Taliban after America invaded Afghanistan a month later in the wake of the attacks.


Patrick Quinn contributed from Kabul.