An Afghan police commander and 13 junior officers have joined the Taliban in the western Afghan province of Farah, the BBC reports.
The commander named as Mirwais, was in charge of a 20-man checkpoint when he defected on Sunday.
The men are said to have taken heavy weaponry, radios and police vehicles including US-made armoured Humvees.
Farah is one of the most insecure areas in the relatively peaceful west.
The commander was based in Shewan village in the district of Bala Bulak, which was until recently considered a Taliban stronghold.
The insurgents were driven out of the area following a series of operations carried out by Afghan security forces.
But local officials said insurgents have regrouped in the area recently.
Police and intelligence officials deployed in the province said the commander poisoned seven policemen in his charge who had refused to defect along with him.
“Mirwais and his policemen had joined the force nearly two-and-a-half years ago. Mirwais had fought the insurgents in this area for quite some time,” an Afghan intelligence official in the region told the BBC.
“Long before he defected, he must have been passing intelligence and crucial information to the insurgents,” the official said.
Officials said that the equipment taken by the defectors – rocket-propelled grenades, heavy machine-guns, radios and police vehicles, including two Humvees – will be a major boost to the Taliban in the area.
Humvees are prized trophies among Taliban commanders, both for their symbolic value and practical ability to travel over rough ground with armoured protection.
The incident is believed to be the biggest police defection to the insurgents. Over the past few years similar incidents have taken place on a much smaller scale in the southern provinces of Kandahar, Helmand, Zabul, Uruzgan and in Ghor, Farah, Badghis and Herat in the west.
Such incidents have rarely been reported in the Afghan media.
International forces have recently had increasing success in persuading Taliban fighters to come over to the government side.