Defence Minister Kim Tae-young said military authorities have not ruled out North Korean involvement in the sinking of the Cheonan, which split apart within minutes after an explosion in the rear hull late Friday night.
Fifty-eight crew members were rescued from the Yellow Sea waters near Baengnyeong Island west of Seoul, but 46 others are believed trapped inside a rear segment of the ship with almost no chance of survival.
Divers rapping on the stern with hammers got no response Monday, military officials said.
South Korean officials have been careful to say the exact cause of the explosion remains unknown, and that the rescue mission is still the top priority.
However, Kim told lawmakers in a frank update Monday in Seoul that North Korean involvement was one possibility.
“North Korea may have intentionally floated underwater mines to inflict damage on us,” he said.
A mine placed by North Korea during the 1950-53 Korean War may also have struck the ship, he said.
North Korea planted about 3,000 Soviet-made mines off both coasts during the war, he said. There are no South Korean mines off the west coast, he said.
Officials have also said an internal malfunction may also be to blame.
Source: CBC AP News