A Russian fighter jet flew within 10 feet (3 meters) of a US Navy surveillance aircraft, in what US officials called an unsafe intercept over the Black Sea, the Pentagon said on Wednesday.

US Navy Captain Jeff Davis, a Pentagon spokesman, said the Russian SU-27 fighter made the maneuver on Wednesday near a US Navy P-8A Poseidon aircraft that was conducting operations in reportedly international airspace.

Russian Defense Ministry Spokesman Major General Igor Konashenkov said on Wednesday that the Poseidon aircraft did not have its transponders turned on, and that it approached Russia's southern border twice.

He said Russian jets were deployed to intercept the incoming aircraft and "Russian pilots acted in strict compliance with international flight rules".

Konashenkov said Russia had to scramble Crimea-based SU-27 fighter jets to intercept the US spy plane. A Sputnik report said the US aircraft made attempts to approach the Russian airspace over the Black Sea while flying with switched off transponders.

US Navy Captain Danny Hernandez, spokesman for the US European Command, said the Navy Poseidon had its transponder turned on during the entire flight, following international law for flight safety.

According to the US, Russian jets conducted four intercepts of US aircraft in the last day, and the one that it considered unsafe lasted about 19 minutes.

Davis said that US Navy aircraft and ships routinely interact with Russian units in the area and most interactions are safe and professional.

"However, we have concerns when there is an unsafe maneuver like this," he said. "These actions have the potential to unnecessarily escalate tensions, and could result in a miscalculation or accident."

It was not the first time for such encounters. In June, the two countries traded accusations over who was to blame for ships from each country getting dangerously close to each other in the Mediterranean Sea. In January, the Pentagon accused a Russian fighter jet flew within 15 feet of a US reconnaissance plane over the Black Sea.

Ap - Xinhua