A South Korean navy ship has sunk near the border with North Korea after an unexplained explosion, which snapped the 88m-long ship in two.

When the explosion occurred, the 1,200t Cheonan navy corvette was carrying a crew of 104, of which, 46 sailors are still missing, according to yonhap news agency.

Early military reports said 58 sailors were rescued from near Baengnyeong island by several navy and coastguard vessels.

Experts believe the stored munitions could have caused the explosion, while others believe that the vessel was sunk by a naval mine or torpedo, however, the exact reason is yet to be determined.