Aerial footage has been released showing the work of emergency services to try and rescue the hundreds of people trapped inside the capsized ferry off the coast of South Korea.

South Korea's government has said 295 people were missing several hours after the ferry sank, raising fears hundreds of children could be trapped inside the vessel.

Initial reports had said rescuers plucked 368 people from freezing waters as the passengers, mostly school students, jumped out when the vessel started sinking.

There were 325 students on board the 6,325-tonne vessel, which capsized fully in about two hours.