No NATO troops were killed or injured in the attack in a village in Tagab district in the province, northeast of the capital Kabul, a spokesman for NATO’s US-led International Security Assistance Force said.
The explosion destroyed the wall of a house, killing four civilians inside, while a passerby on a motorcycle also died and 15 people were wounded, said the provincial police chief of security, Abdul Jalil Shamal.
A spokesman for Taliban insurgents, Zabihullah Mujahid, said in a text message to AFP that 12 American troops had been killed and wounded. The Taliban regularly exaggerate their battlefield actions.
French combat troops pulled out of the strategic province last year as part of an early withdrawal from the country, with all NATO combat forces due to leave Afghanistan by the end of 2014.
High-profile targets in Kabul have been attacked twice in the past 10 days.
On Monday, a Taliban suicide squad stormed the traffic police headquarters at dawn, killing three police officers and unleashing a stand-off that lasted for more than eight hours.
Less than a week earlier, a squad of suicide bombers attacked the Afghan intelligence agency headquarters, killing at least one guard and wounding dozens of civilians.
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