Four more bodies have been found after crews recovered a tourist boat that sank on the Danube in the Hungarian capital last month.

Rescue teams used a large crane to hoist the 50-tonne Mermaid vessel out of the river in Budapest on Tuesday.

After raising the remains of the ship to water level, specialized diver teams were able to enter to search for victims.

Four bodies were recovered from inside the ship, bringing the total to 24 dead and four missing.

The body of one man was found in the locality of Harta, some 100 kilometers downstream from Budapest, around a week ago.

Although they have not yet been formally identified, authorities said that one is believed to be the boat’s Hungarian captain and another is a Korean child, the only minor on board.

The sightseeing boat was carrying South Korean tourists when it was hit by another vessel, the Viking Sigyn cruise ship, and sank on May 29.

At the time the city was swamped by a heavy downpour.

There were a total of 33 people onboard, a group of 31 South Korean tourists and two Hungarian guides.

Seven survivors were rescued from the water on the day of the tragedy.

Rescue efforts have been hampered due to a swollen river, strong currents and reduced underwater visibility.

Authorities were forced to wait for the water level of the Danube to drop so that "Clark Adam," a large crane capable of lifting up to 200 tonnes, could get to the location of the accident and travel under the river's bridges.

The works have focused on the Margarita Bridge, where the ship was wrecked.

Days after the crane was brought into position, work began to lift the wreckage with pumps removing water from the hull, which lasted six hours.

The boat was finally lifted clear of the water and placed on a barge for transport to a port south of Budapest, according to police spokesman Kristóf Gál.

An investigation has been opened into the causes of the incident and authorities will now inspect the remains of the ship.

The 64-year-old Ukrainian captain of the Viking Sigyn has been taken into custody. EFE-EPA