SEOUL - Five sailors were killed Thursday after a Coast Guard boat carrying them in seas off the southern island of Jeju capsized during a rescue operation for a Malaysian-flagged cargo vessel, the Coast Guard said.

The Coast Guard boat, which capsized in waters about 27.7 kilometers off the west coast of Jeju Island at 12:26 pm, was transferring 11 sailors from the ill-fated Malaysian freighter to a rescue ship when high waves turned it over, according to Yonhap News Agency.

A South Korean Coast Guard boat capsizes in waters about 27.7 kilometers off the west coast of Jeju Island at 12:26 pm on Thursday, as transfers 11 sailors from the ill-fated Malaysian freighter to a rescue ship when high waves turned it over. [Photo/Xinhua]

Three of the dead sailors were from the Philippines, while the two others were Chinese, the Coast Guard said. The Chinese Consulate-General in Jeju has confirmed that two Chinese crew members were killed.

The boat was on a rescue mission, with other accompanying vessels, for the Malaysian freighter heading to Singapore, which had sought the Coast Guard's because it began taking on water, Yonhap said.

Six South Korean Coast Guard officers were also aboard the boat. One of the officers lost and later regained consciousness and is receiving treatment at a Jeju hospital, the Coast Guard said.

The freighter, which was carrying 13 Chinese and six Filipino sailors, sank at around 3:50 pm, said the Coast Guard.

A Malaysian-flagged cargo vessel turns over by high waves on Oct 18, 2012. [Photo/Xinhua]