"US Central Command is aware of the reports of a US aircraft crash in Afghanistan", Riordan said. "We are currently monitoring the situation and will provide additional information when possible".
Earlier in the day, the Taliban* movement claimed that a US plane on an "intelligence mission" had crashed in the Afghan province of Ghazni.
Zabihullah Mujahid, a Taliban spokesman, said in a statement that all of the passengers on board the plane, including several senior US CIA officers, were killed in the crash.
Afghan authorities said the plane crashed at around 1:30 p.m. (09:00 GMT) in Ghazni's Deh Yak district. Afghanistan's Civil Aviation Authority, in turn, said in a statement that the crashed plane was not civilian, adding that it was closely following the situation.
Media reported earlier in the day that an Ariana Afghan Airlines aircraft had crashed in Ghazni, but the company denied that it was one of their planes. Meanwhile, according to a source, it was an Afghan National Army aircraft.
*Taliban is a terrorist group banned in Russia