File photo:Xinhua

A senior Iranian military commander on Saturday warned foreign countries against "spying" acts on an ongoing joint naval exercise, Tasnim news agency reported.

On Friday, China, Russia and Iran began a four-day joint military exercise in the Indian Ocean and the Gulf of Oman.

Deputy Chief of Iran's Army for Coordination Habibollah Sayyari said that "many countries are definitely seeking to know what the matter is. Spies have also taken action."

Sayyari said, "We will hit whatever spying craft in the war game zone."