A South Korean court has sentenced a former coast guard officer to four years in prison for negligence in the course of rescue operations during last year's ferry sinking that killed more than 300 people.

Kim Kyung-il was the captain of a coast guard ship dispatched to the scene on the day of the April 16 sinking.

Unprofessional rescue work by the coast guard has been considered as one of the main reasons for the disaster, together with ferry crew members' negligence, overloaded cargo and improper storage. Most of the dead were students on a school trip.

The Gwangju District Court said Wednesday the death toll must have been smaller if Kim had issued an evacuation order for those trapped inside the sinking ship after his arrival at the area.