WASHINGTON/ANKARA (REUTERS) - An unarmed Iranian drone flew directly over a US aircraft carrier operating in international waters in the Gulf this month in a move that was "abnormal and unprofessional," the US military said on Friday.

Iranian state television said a surveillance drone flew over a US aircraft carrier in the Gulf and took "precise" pictures during an Iranian naval drill on Friday.

But a US Navy spokeswoman only confirmed an incident on Jan 12, when an unarmed Iranian drone flew directly over the USS Harry S. Truman. She could not confirm if it was the same incident reported by Iranian media.

The Jan 12 overflight took place the same day Iran detained 10 US sailors who it said had entered Iranian territorial waters by mistake.

The drone initially flew toward the French carrier the Charles de Gaulle, and then flew directly over the USS Harry S. Truman, said the spokeswoman, Lieutenant-Commander Nicole Schwegman, in an e-mailed statement.

The US carrier was not conducting flight operations at the time, Schwegman said.

"The UAV (unmanned aerial vehicle) was unarmed and posed no risk to the carrier's flight operations," Schwegman said.

"While the Iranian UAV's actions posed no danger to the ship, it was, however, abnormal and unprofessional."

Both the American and French carriers were operating in international waters in the Gulf, Schwegman said.

The commander of Iran's navy, Admiral Habibollah Sayyari, said the drone overflight reported by Iranian media as occurring on Friday was a sign of the Iranian navy's "readiness and bravery," according to state television.

An Iranian submarine was also deployed to the area on Friday and took pictures of the drone and the US carrier, the semi-official Fars news agency reported.