Pentagon Bryan Whitman said he hasn't "heard anything like that."

All aircraft in the region are accounted for and we have no reports of any aircraft landing in Iran," said another US official.

Earlier, Iran's state-run Fars news agency said a US military aircraft was forced to land in Iran after violating Iran's airspace,

The report said the plane was carrying five US generals and three nonmilitary passengers and they were questioned before being released and allowed to leave for Afghanistan, which was their destination.