The Ukrainian captain of the Viking Sigyn is expected to be charged by Hungarian prosecutors after the river ship collided with a small tourist vessel on the Danube River, killing 28 tourists on May 29.

The tourist boat had 35 people onboard when it sank in seconds after the river ship hit the vessel from behind during heavy rain and flooding.

The incident occurred near Budapest’s famous Parliament House, which is one of the busiest stretches of river in Europe.

Lawyers for the Ukrainian captain, who is identified by police as 64-year-old Yuriy C. from Odessa, has been in custody since he was arrested after the incident. They said he is devastated but did nothing wrong.

“The (cruiser) captain was definitely in the control cabin at the time of the accident,” Budapest deputy police chief Adrian Pal told a news conference announcing their investigation had been concluded.

“Neither alcohol nor other psychoactive substances could be detected in his bloodstream,” Mr Pal said.

“He just did not notice the Mermaid, simple as that. He never saw it before he hit it.”

Police on Tuesday transferred the case to prosecutors and proposed pressing formal charges against the captain.

Prosecution spokesman Ferenc Rab said that prosecutors would prepare and submit charges after a mandatory 30-day waiting period, adding the captain would remain in custody to prevent him escaping.

The precise charges will be determined by the prosecutor. But police were investigating him on suspicion of misconduct leading to mass casualties and 35 counts of failing to provide assistance.