Gunmen abducted 16 mine-clearing personnel working for the United Nations in eastern Afghanistan, a provincial police chief said Sunday. The men were kidnapped as they traveled between Paktia and Khost provinces on Saturday, said Paktia's police chief Azizullah Wardak. While insurgents operate in the area, Wardak could not say who was responsible for the kidnapping. Similar incidents have happened twice before in Paktia but were resolved successfully, he said. Wardak criticized the demining team, part of the U.N.'s effort to rid the country of decades of planted land mines _ for going into the area without informing the police. All of those kidnapped were Afghans. Afghanistan is one of the most heavily mined countries in the world, and the increase in violence amid a thriving Taliban insurgency has slowed clearance work. Some 50 people are killed and maimed by mines every month. Two-thirds of the country's mines have been cleared over the past two decades, with the rest expected to be removed by 2013. But experts fear Afghanistan can no longer meet that goal because of increased fighting and a drop in international funding. Trained deminers have increasingly been targeted and killed by militants. Last year, insurgents shot and killed six mine clearers in one day and two the next, according to the United Nations Mine Action Center. Militants often use the raw materials from the mines to make roadside bombs and other improvised explosive devices. Mines in Afghanistan are a legacy of decades of Soviet occupation and subsequent civil war. Tens of thousands of mines and unexploded ordinance still pepper the rugged country. Last year, 84,900 mines and 2.5 million unexploded bombs were cleared.