JINDO, South Korea, April 22 -- Death toll in the South Korean ferry sinking accident surged on Tuesday night to 121 as divers were intensively searching inside the submerged hull.

So far, 121 people have been confirmed dead, and 181 others were still missing. The number of the rescued was changed at 174. The seventh day into the search, no survivors or survival signals have been reported yet.

On Tuesday alone, 36 bodies were pulled out of the submerged hull as divers made an intensive search operation into passengers cabins and convenience facilities on the third and fourth floors of the five-story vessel. A day ago, 28 bodies were found in and around the ship.

Many bodies were found in the third-floor lounge and the fourth- floor cabins where students were staying when the ship began to capsize.

The 6,825-ton ferry Sewol capsized and sank off Jindo Island, a southwestern tip of South Korea, Wednesday. The ship carried 476 passengers, including 325 Danwon High School students.

Convenience facilities on the third floor are comprised of singing rooms, a dining hall and lounge where students were believed to be given free time for breakfast when the ship was sinking.

Search operations began to gather steam from Monday thanks to favorable weather conditions and guideline ropes.

Five ropes were installed Sunday to guide divers against rapid currents into the sunken ferry, enabling divers to enter the hull at a faster pace than before. Two ropes were installed on the bow side, with two on the stern side and one in the middle of the ship. Five to six ropes were planned to be snaked into the hull.

Divers entered inside the hull along their respective guideline ropes simultaneously, resulting in random discovery and retrieval of bodies trapped inside the ship.

Climatic conditions are forecast to be favorable for search operations. Tidal currents were forecast to slow down in the area, which is famous for the country's second-fastest currents, from Monday to Thursday.

More than 750 divers will be dispatched to search bodies and possible survivors inside the ship, while 239 rescue ships and 32 airplanes will be deployed near the scene.

Ships and airplanes were scouring the waters as bodies from the vessel were floating. Most ships were searching all the waters within a 1km radius, while four draggers were trawling the waters outside the range.

Rescue efforts were aided by unmanned submersibles called remotely-operated vehicle (ROV). They were used to search the hull where divers were unable to enter. Salvage barges were deployed near the sunken vessel to let divers take a rest and plunge again into the waters.

A total of 25 ships have been deployed to clean up the waters as oil leaked out of the capsized ship on Saturday. Jigging fishing boats, which catch squids, assisted in overnight search to offer lightening for nighttime operations.

Koh Myung-seok, spokesman of the pan-government response center, said earlier that the number of passengers on board the vessel could be changed in accordance with search and rescue operations, noting the figure would be flexible.

Asked whether it was not a fixed number, he said it was not a final figure, indicating readings for the missing can be revised. Koh cited some variables such as the incorrect list of passengers submitted by the ship's operator and unregistered passengers with a vehicle.

Under local regulations, passengers with a vehicle are allowed to board the ship by registering their plate number.

Touching on the three foreign bodies, which were retrieved on Monday night, the spokesman said the authorities informed the Chinese embassy of the two bodies being Chinese men, but he said that the third body, which was earlier known to be a Russian school girl, had yet to be confirmed.

The tax authorities launched a special inspection into families of the ferry's owner on Tuesday, raiding offices of the operator and its affiliates. The tax agency reportedly planned to investigate into documents and computers seized for possible tax evasion and slush funds.