KABUL  - Six people including four Afghan policemen were poisoned and shot dead at a post in the southern province of Helmand, police said Tuesday.

The deaths come days after a policeman in the eastern province of Paktika poisoned and then shot dead nine of his colleagues while they slept.

Helmand police chief Ahmad Nabi Elham said: “Last evening in Nahri Sarraj district in a police post, four police and two guests were first poisoned and then killed. “Three police are missing,” along with a vehicle and some weapons, he added. “We don’t know if the three missing are involved in the poisoning or if the militants have taken them away. The investigation is ongoing.”

Police at the scene later clashed with insurgents, leaving two militants dead, he said. The Taliban said they had killed 10 police in an attack on a post in the district. The insurgents, who have been fighting the Western-backed government of President Hamid Karzai for more than a decade, regularly exaggerate their claims. Killings by Afghan security personnel of their local and foreign colleagues have ramped up tensions between the allies even as NATO-led forces prepare to pull out of Afghanistan by the end of 2014.