KABUL: Taliban militants killed six Afghan police officers on Tuesday, officials said, the latest in a series of attacks on local security forces highlighting the challenges they face as Nato combat troops depart.

The attack on a police post in Logar province south of Kabul came a day after militants ambushed a convoy in the north and killed 22 policemen.

Foreign combat troops are pulling out of Afghanistan by the end of the year, leaving local soldiers and police to battle the persistent Taliban insurgency on their own.

“A group of Taliban attacked a local police post in Baraki Barak district early in the morning and killed six police,” district chief Mohammad Rahim Amin told AFP.

“They fought till the last bullet, but they were finally overpowered by Taliban.” Din Mohammad Darwish, the provincial governor's spokesman, confirmed the attack and said the incident was under investigation.

The Taliban, who have waged a bloody fight against Nato and Afghan government forces over the past 13 years, claimed responsibility for the attack via a known Twitter account.

Interior Minister Omar Daudzai on Tuesday told a gathering of security commanders that a lack of proper weapons was hampering the police and causing heavy casualties.

“Police do not have proper arms. The enemies attack police posts with heavy guns while police defend with AK47s,” he said.

There have been persistent concerns about whether Afghan forces will have the wherewithal to subdue the Taliban without the backing of US-led Nato forces.

Afghan casualties have rocketed over the past two years as Nato has handed over most combat duties to the nation's police and army.

The new President Ashraf Ghani has signed a long-delayed agreement allowing about 13,000 foreign troops to stay on into 2015.

But the follow-up mission, which will take over on January 1 — 9,800 US troops and about 3,000 soldiers from Germany, Italy and other Nato members — will focus mainly on training local forces and counter-terrorism operations.

Also on Tuesday a sticky bomb attached to a car detonated in Kabul and wounded two civilians, the interior ministry said.