South Korea's Hanjin Shipping Co's container carrier "Hanjin Tianjin" is seen in this undated handout photo released by Yonhap news agency on April 21, 2011. [Photo/Agencies]

SEOUL, South Korea - South Korean commandos stormed a container ship hours after it was attacked by pirates in the Indian Ocean on Thursday and freed all crew members unharmed, officials said.

A second ship, an Italian-flagged vessel with 21 crew, was also hijacked by Somali pirates Thursday, the European Union's anti-piracy task force said.

Hanjin Shipping Co spokeswoman Sonya Cho said the South Korean commando raid was carried out by the Choi Young, a helicopter-carrying warship with a crew of 200.

She said the pirates who attacked the 75,000-ton Hanjin Tianjin about 250 miles (400 kilometers) east of Yemen's Socotra island were not found by the commandos.

The South Korean ship sustained "some damage" in the attack but the 14 South Korean and six Indonesian crew members retreated to a specially designed shelter and were unhurt, she said.

"Our crew stopped the engine and hid in the citadel to protect themselves from the pirate attack," she said.

Cmdr. Paddy O'Kennedy of the European Union Naval Force said according to his information the ship was attacked, but there was no solid confirmation that pirates had boarded it.

"The Koreans boarded the ship but there were no pirates on board," he said.

Hanjin said it had lost contact with the ship earlier in the day after it sent a coded distress message indicating it had been attacked by pirates.

Cho Byung-jae, a spokesman for South Korea's Ministry of Foreign Affairs and Trade, confirmed that the Choi Young had been deployed for a possible rescue attempt.

"It has been our government's consistent position that we do not negotiate with pirates," he said. "This will not change."

In recent years Somali pirates operating off the east African coast have hijacked at least eight South Korean ships, all of which were released, many after South Korean companies paid a ransom.

In January, however, South Korean commandos attacked the Samho Jewelry after it had been hijacked, killing eight pirates and arresting five others, with no loss of life to crew members. The surviving pirates were brought back to South Korea and are awaiting trial.

Also Thursday, the European Union's anti-piracy task force said Somali pirates hijacked the Italian-flagged MV Rosalia D'Amato as it sailed about 400 miles (650 kilometers) southeast of the Omani port of Salalah in the Indian Ocean.

It said the 74,500-ton ship was on its way to Iran from Brazil when it was attacked by a single skiff.

Coalition warships had contacted the vessel but were told to stay away as pirates had already boarded the vessel, it said.

There was no further information on the status of the ship's six Italian and 15 Filipino crew members.

The task force also said Thursday that it had returned 18 suspected pirates to Somalia after several countries with an interest in their case declined to prosecute them.

The suspects were detained after an attack April 5 on the Singapore-flagged MV Pacific Opal.

The task force did not name the countries, but normally nations that seize pirates have the right to prosecute them or request other states to put them on trial on their behalf.

Many countries are unwilling to shoulder the burden of a court case or face possible reprisals from other pirates.

According to the UN Office on Drugs and Crime's anti-piracy initiative, more than 1,000 Somalis have been convicted or are on trial for suspected piracy.