Reports suggest the attacking militants had travelled from the nearby southern province of Helmand, where British forces are struggling to hold down a difficult security situation.
Meanwhile, in the eastern province of Ghasni, at least five policemen died following the detonation of a roadside bomb.
The attacks continue an upturn in the rate of attacks in the country, following pledges of a "spring offensive" by Taliban leaders.
Elsewhere in the country a kidnapped French hostage is waiting to discover whether or not he will be executed by his captors.
Eric Damfreville of children's charity Terre d'Enfance was captured on April 3rd in Nimroz province and faces a potential death sentence – together with three Afghans - if France does not agree to a troop withdrawal from the country and prisoner exchanges.
Following an earlier extension of the deadline, the Taliban has extended it still further because of the French presidential election.
"The policy of the Taliban movement regarding the foreign hostages is clear: if our demands are not met, we will act based on our policy that we have implemented with foreigners so far," an official was quoted as saying by the AFP news agency, implying a likely execution for Mr Damfreville.
Italian journalist Daniele Mastrogiacomo was freed in exchange for the release of Taliban militants last month.
Afghan president Hamid Karzai said after Ms Mastrogiacomo's release that no further exchanges would take place.
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