BAGHDAD, JUNE 24 -- -- Iraq said its forces hit a ship with rocket fire today near Iran's main oil export terminal at Kharg Island. It was the third Iraqi attack on Persian Gulf shipping in five days.

In London, Lloyd's Shipping Intelligence Unit said the 30,600-ton Turkish vessel Hira III was hit by an Iraqi missile off the Iranian coast and seven crewmen were injured.

It was not clear whether the Iraqi and Lloyd's reports referred to the same attack. Iraq customarily uses "large maritime target" to describe supertankers, which are far larger than the Turkish vessel mentioned by Lloyd's.

Tehran's official Islamic Republic News Agency (IRNA) said Iranian jet fighters shot down an Iraqi helicopter early today after it attacked a merchant ship near Bushehr. Again it was not clear whether the reports referred to the same incident.

Until Saturday, Iraq had left ship traffic alone since its May 17 missile attack on the frigate USS Stark, which killed 37 sailors. Iraq said the attack was a mistake.

Military spokesmen said Iraqi "naval units" rocketed a "large maritime target" early today near Kharg. It called the raid an "implementation of Iraq's resolve to cut off the enemy's oil supplies used for prolongation of the war," which began in September 1980.

Marine salvage executives in the gulf region said the Hira III was hit about 10 miles off Bushehr. The port is near Kharg, which is Iran's main oil export terminal and a prime target of Iraqi air raids.

IRNA quoted a military communique as saying a French-built Super Frelon helicopter was shot down just before 1 a.m. and crashed into the sea near Bushehr.

Iraq uses Super Frelons armed with French-made AM38 antiship missiles to attack Iranian targets in the northern Persian Gulf.

Its jet fighter-bombers hit the Liberian-registered tanker Tenacity on Saturday and another vessel on Tuesday that has not yet been identified.

In Baghdad, military spokesmen said Iraqi aircraft flew 22 combat missions today against Iranian ground targets along the 730-mile border warfront. They reported only "minor skirmishes" in Iraqi Kurdistan, where Iran claims victories in a five-day-old offensive.

Reports from Tehran said Iranian forces smashed an Iraqi counterattack in the area 170 miles north of Baghdad, killing or wounding many enemy soldiers.

Conflicting claims in the war seldom can be confirmed independently because foreign journalists are allowed into battle zones only on rare guided tours.