At least 64 people have died in the accident and 238 are still not found, the South Korean coast guard updated on Monday.
The search and rescue operation has managed to pull some 179 people to safety since the 6,825-tonne ferry sank last Wednesday carrying 476 passengers and crew.
The ferry Sewol had sailed out of the western port of Incheon on Tuesday evening but ran into trouble some 20 kilometres off the island of Byungpoong.
South Korean president Park Geun-hye on Sunday declared the cities of Ansan and Jindo as special disaster zones eligible for national disaster assistance programs, in order to facilitate central government help, a spokesman for the Joint Task Force Headquarters said in a news release.
Meanwhile, Lee Joon-seok, captain of the ill-fated ferry, has been charged with abandoning his boat, negligence, not seeking rescue from other ships and violating seamen's law, state media reported.
The charges for Lee were brought forth despite investigations showing that he was not in the steering room when the accident took place. At the helm of Sewol during the accident was a third mate, who is also facing charges including negligence and causing injuries and leading to deaths.