Kabul, Afghanistan (CNN) -- Religious materials -- including Qurans that were burned at Bagram Airfield in Afghanistan, sparking Afghan protests -- were removed from the library of a detainee center "because of extremist inscriptions" on them, a military official said Tuesday. There was "an appearance that these documents were being used to facilitate extremist communications," a military official said. "Additionally, some of the documents were extremist in and of themselves, apparently originating from outside of Afghanistan," the official said. The official said the material was burned, but authorities are attempting to determine how much. The uproar prompted Gen. John Allen, commander of NATO's International Security Assistance Force, to issue a directive "that all coalition forces in Afghanistan will complete training in the proper handling of religious materials no later than March 3," the NATO-led force said..
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NEW: Commander of NATO-led force mandates training on handling religious materials
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Official: Some documents were "extremist in and of themselves"
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Commander Gen. John Allen says he has launched an investigation
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Muslims regard the Quran as their holy book
Local citizens who work at the base discovered the material that had been put into a burn pit by @placeholder personnel and alerted officials.