South Korea's prime minister on Wednesday called for searches for people believed trapped inside a sunken ferry to be completed by the weekend.

More than 30 people are listed as missing three weeks after the Sewol carrying 476 people sank off South Korea's south coast. Slow searches have deepened the anguish of families of missing people, who have been camping out at a nearby port waiting for the news of their loved ones. About 270 dead bodies have been recovered. Only 174 survived.

Prime Minister Chung Hong-won told a Cabinet Council meeting that officials must work with "resolve to finish searches" by Saturday to help ease the suffering of relatives of missing people as tidal currents are forecast to be weak until then.

Most of the dead and missing were from a single high school near Seoul, and were heading to the southern tourist island of Jeju.

Searches have been hampered by strong currents, bad weather and floating debris inside the ship. A civilian diver fell unconscious while searching and died on Tuesday, the first fatality among divers mobilized since the sinking.

All 15 surviving crew members involved in the ferry's navigation have been arrested, accused of negligence and failing to protect passengers. Improper stowage and overloading of cargo is suspected as a possible reason the ferry sank, and four employees at the ship's owner who handled cargo on the Sewol have also been arrested.