A South Korean cargo plane has crashed in waters off South Korea's southern Jeju island killing two people.

The Yonhap news agency quotes the coast guard as saying the Asiana Airlines plane crashed early Thursday.

The Boeing 744 plane with one pilot and one crew member was headed from the Incheon International Airport to Pudong in east China. Officials say it was returning to Jeju International Airport after reporting mechanical difficulties.

Yonhap says a coast guard patrol boat found the debris of the aircraft in waters about 100 kilometers west of the city of Jeju.