KABUL, Afghanistan - Nine NATO service members were killed Thursday in Afghanistan, including seven U.S. troops who died when a powerful bomb exploded in a field where they were patrolling on foot, officials said.
Two Afghan policemen also died and two others were wounded in the explosion in the mountainous Shorabak district of Kandahar province, 12 miles from the Pakistan border, said Gen. Abdul Raziq, chief of the Afghan border police in the province.
"Two months ago, we cleared this area of terrorists, but still they are active there," Raziq said.
The Taliban claimed responsibility for the blast.
"A bomb was planted for them in a field," Taliban spokesman Qari Yousef Ahmadi said in a telephone call.
A U.S. official, speaking on condition of anonymity because he was not authorized to disclose the information, confirmed that seven American service members died in the bombing. One other NATO member also was killed in the blast.
The international military coalition reported that one additional NATO service member was killed Thursday when a helicopter crashed in the east.
It was the deadliest day for coalition forces in Afghanistan since April 27, when a veteran Afghan military pilot opened fire at Kabul airport and killed eight U.S. troops and an American civilian contractor.
Thursday's blast was the worst single attack against NATO forces by one of the Taliban's crude, homemade bombs since October 2009. Seven soldiers from a unit based in Fort Lewis, Wash., died Oct. 27, 2009, when their vehicle hit a roadside bomb in Arghandab district, also in Kandahar province.
In all, 1,586 U.S. military personnel have died serving in the Afghan mission, according to the website icasualties.org.
Roadside bombs killed 268 American troops in Afghanistan last year, a 60 percent increase over the previous year, even as the Pentagon employed new measures to counter the Taliban's makeshift weapon of choice. Defense officials attributed the rise in casualties to the surge in U.S. forces in Afghanistan last year.
The number of U.S. troops wounded by improvised explosive devices also soared, according to the most recent U.S. defense figures. There were 3,366 U.S. service members injured in IED blasts - up from the 1,211 hurt by the crudely made bombs in 2009, the figures show.
Officials with the Pentagon's Joint Improvised Explosive Device Defeat Organization, based outside Washington, has said that additional explosives sensors, bomb analysts, and specially trained dogs have helped battle the roadside bombs.
Last year, the Pentagon provided $495 million to buy 34 tethered surveillance blimps that give troops a bird's-eye view of certain areas and sent in more unmanned surveillance aircraft so route-clearance patrols would have the benefit of full-motion video. The Pentagon also delivered more than 5,000 handheld bomb detectors, improved training, and sent additional equipment to Afghanistan to counter the threat.
On May 1, insurgents declared the start of a spring offensive against NATO and the Afghan government. NATO has been expecting the Taliban to stage a series of spectacular and complex attacks, and the group has already carried out a number of them recently.