By Marton Dunai and Krisztina Than
BUDAPEST (Reuters) - Hungarian rescue officials said there was little chance of finding survivors after a boat with South Korean tourists on board sank on the Danube River in Budapest, with seven people confirmed dead and 21 missing.
The boat was cruising when it collided with a larger luxury passenger boat during a rainstorm on Wednesday evening, causing it to capsize and sink with 33 South Korean tourists and tour guides and two Hungarian crew aboard.
"I wouldn't say there is no hope, rather that there is a minimal chance (of finding survivors)," Pal Gyorfi, a spokesman for the Hungarian national ambulance service, told the M1 state broadcaster.
"This is not just because of the water temperature, but (also) the strong currents in the river, the vapour above the water surface, as well as the clothes worn by the people who fell in," he added.
Police said the smaller boat turned on its side and sank within seconds of the collision under a bridge near Hungary's parliament building.
They said a criminal investigation was under way to determine the cause of the accident. Police declined to say if the bigger vessel, the 135-metre (443 ft) Viking Sigyn, put out any signals for help.
Police said its investigation yielded evidence that raised personal responsibility, so it questioned the Viking Sigyn captain, a 64-year-old Ukrainian, as a suspect, and later moved to take him into custody for reckless misconduct in waterborne traffic leading to mass casualties.
Police said it initiated the formal arrest of the captain, identified as C. Yuriy from Odessa.
Officials said the hull of the Mermaid, a 27-metre (89-ft) double-decker river cruise boat, had been found on the riverbed a few hundred metres from its usual mooring point.
A crane ship docked near the wreck on Thursday in preparation for recovery operations and divers prepared equipment. Police said the rescue efforts were hampered by high water levels, strong currents and bad visibility.
"Those who were trapped in the hull or were stuck underneath can be lifted only once the wreckage is pulled out," a police statement said.
Hungarian Prime Minister Viktor Orban offered his condolences to Seoul. South Korean President Moon Jae-in said the authorities would work with the Hungarian government to investigate the cause of the accident.
"What's most important is speed," Moon said in Seoul.
Some South Korean relatives of those on board started to depart for Hungary. Several family members were seen at Incheon International Airport in Seoul on Thursday night.
South Korean rescue teams and officials including South Korean Foreign Minister Kang Kyung-wha also left for Budapest on Thursday. She will hold a news conference with Hungarian Foreign Minister Peter Szijjarto at 0730 GMT on Friday.
For a graphic on capsized Hungarian boat, see: https://tmsnrt.rs/2WezCIB
The foreign ministry said 30 South Korean tourists, including at least one child, three South Korean tour guides and two Hungarian crew were on board when the accident occurred at around 9 p.m. (1900 GMT).
Seven South Koreans were rescued, seven died, and 19 South Koreans were among the 21 missing, said Kang Hyung-shik, a foreign ministry official. The crew members were also missing.
The seven people rescued were suffering from hypothermia but stable, a Hungarian ambulance spokesman said. Police said the seven people who died had no life vests on.
Video footage from a security camera screened by police showed the bigger boat catching up from behind at a higher speed, clipping the Mermaid's left side.
"The (Mermaid) for some reason, turns into the way of the Viking. And the Viking as it bumps into it, pushes it... and within seven seconds ... (Mermaid) sinks," Pal said, describing the video.
Rescue officials deployed boats, divers, floodlights and radar, scouring the river for several kilometres (miles) downstream from the site of the accident.
Police said efforts were hampered by the fast currents of the flooding Danube, whose deep water was full of debris, at 12 degrees Celsius (53.6°F), and flowing at a speedy 10 kilometres (6.2 miles) per hour.
Well-wishers laid flowers outside the South Korean embassy in Budapest, and candles burnt on the Danube bank.
The Mermaid's owner said the boat - a Soviet model manufactured in 1949 and refurbished in the 1980s - had been in its fleet since 2003, with regular maintenance.
"We are mobilising every resource we have to protect human lives," the owner Panorama Deck Ltd. told state media through a spokesman.
The larger Viking Sigyn is a 95-room floating hotel of the kind that has multiplied as Danube river cruises gained popularity in recent years.
"There were no injuries to Viking crew or Viking guests. We are cooperating with the authorities as required," said a spokesperson for operator Swiss-based Viking Cruises Ltd.
(Reporting by Gergely Szakacs, Marton Dunai and Krisztina Than; Additional reporting by Hyonhee Shin, Joyce Lee, Do Gyun Kim and Minwoo Park in SEOUL; Editing by Jon Boyle, Ros Russell and Richard Chang)