

REPORTING FROM KABUL, AFGHANISTAN –- Eight members of the NATO force were killed in southern Afghanistan in a 24-hour period ending Friday, Western military officials said.

NATO's International Security Assistance Force did not disclose the troops’ nationalities, but the majority of those serving in southern Afghanistan are American or British. The south of Afghanistan includes the volatile provinces of Helmand and Kandahar, the traditional heartland of the Taliban.

Four of the eight were killed Friday in a single explosion, the military said in a statement, and a fifth died earlier as the result of an "insurgent attack," a phrase often used to characterize a firefight with Taliban militants.

Late Thursday, military officials had announced that three troops were killed in the south by an improvised explosive device, or IED. The crude but powerful bombs remain the largest single killer of Western troops in Afghanistan.

U.S. troop fatalities in Afghanistan fell in 2011 for the first time in four years, and overall NATO deaths dropped as well. About 10,000 American troops left Afghanistan in the latter part of last year, and 23,000 more are to depart by the end of this year.

American commanders have said they expect the military focus this year to shift to Afghanistan's east, bordering Pakistan's tribal areas. The Haqqani network, considered the most dangerous insurgent group, operates mainly in the east.

But the south, which was the scene of a series of major U.S.-led offensives over the last two years, shows signs of not being pacified. Local officials say insurgents have filtered in to retake ground gained by Western troops in earlier confrontations, and that poppy cultivation and trafficking -- a major revenue source for the Taliban and other militant groups -- appears to be on the rise again.

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-- Laura King

Photo: Taliban fighters put down their weapons after they join Afghan government forces at a ceremony in Herat in western Afghanistan. Credit: Aref Karimi / AFP/Getty Images