South Korea's defence minister has renewed speculation a torpedo could have caused the blast that sank a warship off its coast last week.
Kim Tae-young said it was a "likely possibility" the Cheonan had been hit by such a missile, but that all possibilities needed to be considered.
Mr Kim did not say who would have fired a torpedo or under what circumstances it could have happened.
Rescuers are still searching for 46 sailors missing on board the ship.
Officials say some could be trapped alive in watertight sections of the vessel.
"We'd like to think our sailors were well-trained enough to survive days underwater," said Cdr Song Moo-jin of South Korea's naval salvage unit.
Mr Kim had previously said a sea mine could have caused the blast, which tore the 1,200-tonne corvette in half near Baengnyeong Island, close to the maritime border with North Korea.
But on Fri
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