KABUL -- More than a dozen members of Afghanistan's national police have defected and joined the Taliban in the last few days, Afghan officials told NBC News on Tuesday. 

A police commander in the Shewain area of Farah -- a western province bordering Iran -- led 13 junior Afghan National Police (ANP) members under his command in a mass defection on Saturday night, taking with them weapons and two Humvees, an official told NBC News.

According to another official in Farah, the commander had been with the ANP for two-and-a-half years, and had poisoned seven other police officers who refused to defect with him. Those seven survived.

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It was not the first defection from ANP ranks, although it was among the largest to be reported.

In February 2010, a group of two dozen police officers left their posts in Wardak province to join the Taliban, taking with them weapons and trucks, The New York Times reported.  

A Taliban spokesman later claimed the officers had surrendered to them, the newspaper said.

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Several smaller-scale defections have been reported across the country in recent years.

According to NATO figures, there were 149,642 ANP members serving in various roles across Afghanistan as of April 2012. New members are being trained with a goal of reaching a target strength of 157,000 by October 2012, as NATO troops prepare to withdraw from the country in 2014. 

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