The Iranian navy has freed 28 Chinese crew members less than a day after their cargo ship was hijacked by Somali pirates off the Islamic republic's south coast, Chinese state media said Saturday.

The pirates attacked the ship early Friday in the Gulf of Oman near the Iranian port of Chabahar, clambering onto the vessel with ladders and opening fire, said the official Xinhua news agency, citing China's embassy in Tehran.

It was the latest episode of Chinese getting into trouble as the country's firms do more business abroad -- Chinese workers were kidnapped in Sudan and Egypt earlier this year, and Chinese sailors have been held captive before.

Following the hijacking Friday, China's ambassador in Tehran, Yu Hongyang, demanded swift action from Iran, which dispatched its navy to rescue the crew.

Two warships caught up late Friday with the ship, the Panama-registered Xianghuamen which belongs to a company in eastern China, and the pirates "threw their weapons into the sea and surrendered to the Iranian navy," Xinhua said.

The ambassador had earlier urged Tehran to make the safety of the crew its "first priority", adding that the Chinese government and foreign ministry had expressed concern about the incident.

The freighter, which had set off from Singapore and was heading to a port in southwestern Iran, had its engine damaged in the attack and was being repaired, Xinhua said. It will continue to an Iranian port after repairs.

The waters of the Arabian Sea, at the northern tip of the Indian Ocean, have seen hundreds of pirate attacks in recent years, with Chinese shipping vessels routinely targeted.

China has also been heavily involved in anti-piracy missions in the Gulf of Aden, off the coast of Somalia, and in international waters near the Gulf of Oman.

About 85 percent of China's oil imports are routed via the Gulf of Aden and through the Indian Ocean, making the region extremely important for Chinese trade.

Since 2008, China has sent 10 escort missions and more than 8,000 military personnel to the Gulf of Aden, escorting more than 4,300 vessels in the process, state-run China Daily said last year.

In June last year, a Chinese shipping vessel and a crew of 29 were released by pirates after being held captive for 207 days.

China has also formed military links in Africa and in the Indian Ocean in order to protect its growing economic interests in the region, including its ocean-going transport ships.

In December last year, Beijing not only committed to support Ugandan forces operating in Somalia but also pledged to help the Seychelles fight piracy.

The surge in Chinese going abroad for work has also brought increased danger, with cases of abductions on the rise.

In late January, 29 Chinese workers were kidnapped by rebels in Sudan's South Kordofan state but were freed in good health after 11 days in captivity.

Not long afterwards, 25 Chinese workers were kidnapped in Egypt by Bedouins demanding the release of relatives imprisoned by the fallen regime of Hosni Mubarak. They were soon freed.