Hungary's interior minister and a South Korean official have visited the site at Budapest's Margit Bridge, where rescue crews are using a huge floating crane to lift a sunken tour boat out of the Danube River.
Nineteen South Korean tourists and a Hungarian crewman have previously been confirmed dead, with eight people still missing.
Police spokesman Kristof Gal said although it was not yet officially confirmed, the Hableany's Hungarian captain and a young South Korean girl are believed to be among the four bodies taken off the boat after it was raised to the river surface.
Seven of the 35 people on board were rescued and seven bodies quickly recovered but others were swept away in the swollen river or trapped inside the boat.
Several bodies have been recovered from wreckage during the salvaging of a tour boat that sank in the Danube River in Budapest.
Temperatures above 30 degrees Celsius (86 degrees Fahrenheit) and strong river currents have slowed the operation, which has been stopped several times.
The lifting operation began at around 6 am (0400 GMT) and six hours later the Mermaid tourist boat was nearly entirely out of the water.
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Hungarian investigators carried out another search inside the Viking Sigyn, the cruise ship that hit the tourist boat, to obtain additional evidence amid growing criticism that the investigation into the sinking has not been thorough. Those missing include the Mermaid's Hungarian captain.
Divers entered the sightseeing boat as a floating crane slowly brought it to the surface.
Damage was visible to the rear part of the Mermaid where the collision occurred.
The cruise ship's captain - identified only as Yuriy C.in line with Hungarian laws - has been under arrest since June 1, suspected of endangering water transport leading to a deadly mass accident.
Once out of the water and removed to a secure location the Mermaid will be examined by police who have already launched a criminal probe into the cause of the accident.
On Monday the Sigyn was again searched by Hungarian police.
Dozens of small sightseeing boats ply the river through Budapest every day.