Eight Afghan policemen have been killed in their base by "infiltrators" in an attack claimed by the Taliban in Shinkia district of the southern province of Zabul.
"The infiltrators first poisoned their colleagues and then shot them dead," said provincial spokesman Gul Islam Seyal on Saturday.
The attackers fled the area, he added, taking all the weapons and munitions from the base.
Taliban spokesman Zabihullah Mujahid, however, denied the use of poison.
Some two weeks ago, 11 policemen were shot dead by one Afghan officer in a similar attack at a checkpoint. The assailant in the so-called insider attack fled the checkpoint in Helmand province in a police vehicle.
In a separate incident, three gunmen attacked a military airbase in the eastern province of Khost. Officials said one of the attackers was killed by police before he was able to enter the base close to Afghanistan’s border with Pakistan.
The two others, official said, disappeared after the first attacker was shot. No group has claimed responsibility for the attack.
Earlier a government official said that in 25 hours security forces had killed over 50 militants across Afghanistan.
More than 15 years after the United States invaded Afghanistan, insecurity remains in the country.
Currently 8,400 US troops are stationed in different bases in Afghanistan. Earlier this week, US General Joseph Votel, who is in charge of military operations in the Middle East, asked for even more troops to be deployed to Afghanistan.