Iran has said that an aircraft forced down in its territory was a Hungarian aid plane with no Americans aboard.
The latest information contradicts earlier reports that it was carrying US soldiers.
A senior military official told state television's Al-Alam channel that the incident dated back to 30 September, not on Sunday and Monday as had earlier been reported.
The US military in Baghdad also confirmed that there had been no Americans aboard the aircraft.
US military spokesman Lieutenant David Russell said the airplane was a light transport plane with no Americans onboard.
The White House had previously poured scorn on the Iranian reports, although it had added it was looking into them.
Earlier it had been reported that Iranian aircraft had forced an aircraft carrying US military personnel to land in Iran after it entered its air space without permission.
The semi-official Fars News Agency said the plane had five soldiers and three civilians on board who were subjected to questioning.
They said that after a day's interrogation the people on board were allowed to leave on the plane bound for Afghanistan.
