South Korean defence officials say it is unlikely the sinking of one of its warships involved an attack by North Korea.
Forty six of the crew of 104 remain unaccounted for after an unexplained explosion on board the craft which was on patrol close to Baengnyeong Island near the disputed maritime border between the two nations.
Coastguards plucked 58 sailors from the water after the 12,000 tonne “Cheonan” sank after being holed beneath the waterline by the blast.
South Korean President Lee Myung-bak convened a late-night emergency meeting with his defence ministry officials, saying all possibilities must be looked into.
But investigators have apparently ruled out the possibility of a torpedo strike by the North after examining satellite pictures confirming there were no North Korean vessels in the area.
Initially the incident caused panic on the streets of the South’s capital Seoul as it happened hours after North Korea’s military threatened “unpredictable strikes” against the US and South Korea.