KIEV — An explosion which sank a border patrol boat off Ukraine's strategically important port city of Mariupol was caused by a separatist-made bomb, the Ukrainian military said Monday.
The boat exploded on Sunday, killing one crew member and wounding five others, as it left its mooring station in Mariupol, which is on the Sea of Azov and on the edge of the conflict between Ukrainian forces and Russian-backed separatists.
"The explosion of the patrol boat in the Azov Sea was caused by a rebel homemade bomb," the military said in a statement.
The border guards on the boat spotted the device floating in the water and it exploded as they attempted to pull it on board, the statement said.
Mariupol has been under threat from rebel attacks for months as control of the industrial hub would help the rebels to build a seaboard corridor to the Black Sea peninsula of Crimea, which Russia annexed from Ukraine last year.