Iran is helping train Taliban fighters within its borders, according to U.S. military and intelligence officials.
The United States has already said that the Taliban may be receiving limited training from the Iranians in Afghanistan, but the officials told CNN that training in the use of small arms was occurring within Iran.
"We've known for some time that Iran has been a source for both material and trained fighters for Taliban elements in Afghanistan," said Army Lt. Col. Edward Sholtis on Monday. But, he said, it is unknown whether that training is occurring with the support of Tehran, or it is "simply something that is happening beyond the government's control."
"For some years, Iran has supplied arms and munitions to the Afghan Taliban," said a U.S. intelligence official. "It has also helped conduct at least small-scale weapons training for the Taliban. There's reason to believe that some of this training has occurred in Iran."
The officials who spoke with CNN did not say how many Taliban fighters have been trained in Iran, or whether the training was sanctioned at the highest levels of the Iranian government.
Iran, which has always denied supporting the Taliban, said the training allegations were false.
An Iranian official at the United Nations said these are "...absolutely baseless and wrong allegations, and strongly rejected by the Islamic Republic of Iran."
Gen. David Petraeus, the top U.S. military commander in the region, has said Iran was aiding the Taliban within Afghanistan but that its role was limited in scope.