**At least four Afghan policemen have been killed in an attack in southern Helmand province, officials say.**Reports say their bodies were found near the ministry of information and culture in the regional capital, Lashkar Gah.
The authorities say it is not yet clear who killed the officers. An investigation is under way.
Taliban militants frequently attack Afghan and foreign security forces in southern and eastern Afghanistan.
Hundreds of Afghan police officers have been killed in the past few years.
UK and other Nato troops are set to launch the biggest operation yet in Helmand, the BBC learned on Monday.