South Korea is demanding a swift explanation from the Hungarian government after at least seven of its citizens died in a boat sinking on the River Danube, local media reported.
Twenty-one other South Korean nationals are still missing after the accident, which occurred on Wednesday evening in Budapest.
South Korea will ask Hungary to swiftly determine the cause and identify those responsible, Deputy Foreign Minister Lee Tae Ho said at a government disaster management meeting in Seoul, according to the Yonhap news agency.
The “Hableany” (Mermaid) boat sank with 35 people on board after colliding with a much bigger cruise ship.
Only seven survived and seven bodies had been recovered.
The 64-year-old Ukrainian captain of the Viking Sigyn cruise ship was taken into custody in the course of the investigation, police in Budapest said on Thursday.
He claims that he could not have avoided the accident.
He was charged on Saturday, a Budapest court official told AFP, but gave no further details.
The captain’s lawyer, Balazs Toth, said the court had granted bail, but prosecutors were appealing and so his client remained detained.
“He is devastated by the number of victims and is asking constantly that condolences are conveyed to their families,” Toth said.
“My client has not changed his statement made as a witness. He insists that he has not made any error,” his other lawyer, Gabor Elo, told reporters after the hearing.
The search continues, but not a single survivor or body has been found since shortly after the accident.
Hungarian media reported that divers have been unable to access the submerged wreckage due to rising river levels after days of rain and strong undercurrents.
The conditions also make raising the boat out of the water impossible.
One of the bodies had been found about 11km (seven miles) downstream of the accident site.
The South Korean deputy minister said the identities of the seven victims have been revealed and their families have travelled to the Hungarian capital, Yonhap reported.
The Hungarian Magyar Nemzet daily, meanwhile, has quoted police reports as saying that the Sigyn might not have warned the pilot of smaller ship that he was going to overtake.
According to the newspaper, he also did not alert police about the collision.
People have been laying flowers along the river bank and on a bridge near the collision site, as well as at the South Korean embassy.
On Saturday, black flags were flying along the bridge.