Iran warned off foreign spy planes that tried to approach its forces during naval drills in the Strait of Hormuz, a military spokesman said Tuesday.

The drills, which began Friday, according to Reuters, are aimed at displaying Iran's military prowess in the vital shipping route through which 40 percent of the world's sea-borne oil exports pass.

Iran has threatened to block the strait if it comes under military attack over its disputed nuclear program. The United States has warned it will not tolerate any obstruction of commercial traffic through the strait.

"So far about 30 warnings have been given to reconnaissance and surveillance planes of extra-regional forces that wanted to approach the area where the drills are taking place," Commander Amir Rastegari told the semi-official Mehr news agency, as reported by Reuters.

“Various reconnaissance aircraft that sought to penetrate into the drill area were given warnings by the navy and the air defense force. ... Subsequently, the intelligence planes and drones distanced from the area after receiving the warnings," he said.

Iran is carrying out six days of drills in an area of about 1 million sq km in the Strait of Hormuz, the Gulf of Oman and northern Indian Ocean.

State television reported that naval forces had successfully test fired coast-to-sea and surface-to-surface missiles.

Rastegari told the government’s English-language Press TV that the Qader cruise missile with a range of 200 km had "successfully and precisely hit and destroyed its mock enemy target."

Iran held a similar 10-day drill in December and sent a submarine and a destroyer into the Gulf four months ago just as U.S. and allied navies were conducting exercises in the same waters to practice keeping oil shipping lanes open.

The official Fars news agency quoted a leading MP declaring: “The Iranian armed forces' successful naval wargames in southern waters proved that any enemy aggression against the country's borders would receive a crushing response.”