Iran's state TV says the country's navy has rescued 28 crew members of a Chinese ship hijacked by pirates.

The April 7 broadcast says the Iranian navy also detained nine Somali pirates in the operation in the Arabian Sea in the north of the Indian Ocean.

The pirates attacked the ship on April 6 but they surrendered after Iranian navy sent warships to rescue the crew and free the ship. The freighter was carrying iron and was heading to a port in south-western Iran, Associated Press reports.

Both the attack and the rescue operations were carried out in international waters.

Iran has clashed with pirates on several occasions in the past and freed ships captured by them.