The South Korean warship that sank Friday night after a mysterious explosion may have been hit by a North Korean mine, said the South Korean defence minister Monday.

The minister said a North Korean sea mine could have drifted into the South's waters, adding that investigators are considering the possibility that the mine was intentionally set adrift.

Of more than 100 sailors aboard the ship, 58 were saved. There is little hope that the 46 who are still missing will be found alive. Divers who reached the ship Monday said they heard no signs of life.