A suicide bomber on a motorcycle struck a busy marketplace in eastern Afghanistan Friday, killing at least seven people including an anti-Taliban militia leader, officials said.

The attack, which took place in the Qarabagh district of the insurgency-wracked Ghazni province, also injured seven civilians, deputy provincial police chief Asadullah Insafi told AFP.

"We think that the target of the attack was commander Dawlat Khan, who was martyred along with three of his bodyguards, and three civilians in this attack," Insafi said.

Khan led a group of militiamen who were taking on the Taliban in several villages and planned to join the ranks of the Afghan Local Police (ALP), Insafi added.

The ALP is a village-level force formed in 2010 to provide security in areas where the better-trained national police and army are scarce.

Deputy provincial governor Mohammad Ali Ahmadi confirmed the account saying that seven civilians were also "seriously" wounded in the blast which he described as "huge".

Taliban insurgents have carried out a campaign of assassinations of pro-government figures and warned Afghans to distance themselves from the government.

On Thursday the Taliban -- reportedly helped by infiltrators -- captured at least 12 Afghan policemen from their check-post in the southern province of Zabul and took them to unknown location.

Government forces have formally taken responsibility for security from US-led NATO troops who are due to leave the country next year. But there are concerns about their ability to stand against the Taliban unaided.

Afghanistan's 350,000-strong security forces are suffering a steep rise in attacks as the NATO combat mission winds down.

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