Militants stormed a police post in Deh Yak district of central Ghazni province and killed the six officers as they slept, an official said.
"One of the police who had links with the Taliban let them into the post while other police were sleeping. The Taliban were led to the post and killed six police," district chief, Fazul Ahmad Tolwak told AFP.
"The police who led the Taliban into the post joined the Taliban after the attack and went with them."
He said one officer was wounded but survived the attack. Another police officer was detained over suspected links to the attack and was being investigated, he said.
Fazul Sabawoon, a spokesman for the Ghazni provincial administration also confirmed the incident and said six officers, part of the Afghan Local Police, a US-funded community force, were killed in the pre-dawn raid.
He also blamed an "insider" for the attack.
More than 60 foreign soldiers were killed in 2012 in insider attacks that have bred mistrust and threatened to derail the process of training Afghan forces to take over security duties ahead of Nato's withdrawal next year.
Scores of Afghan forces have also died in the attacks and the threat has become so serious that foreign soldiers working with Afghan forces are regularly watched over by so-called "guardian angel" troops to provide protection.
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