The owner and the captain of a boat on which a 57-year-old Italian tourist died of carbon monoxide poisoning while two children are in a life-threatening condition, were arrested on Wednesday for installing a power unit in the boat's engine-room, which caused a leakage of poisonous gases, police said on Thursday.

The 23-year-old owner of the yacht and its 27-year-old captain, both Croatian nationals, were taken in for questioning by police on the island of Hvar, the Split-Dalmatia County police department said.

They are believed to have installed, on August 8, contrary to professional standards and explicit technical instructions regarding the safety of the device, a petrol engine driven power generator with air conditioning in the boat’s engine-room. The operation of the power generator resulted in the leaking of carbon monoxide into passenger cabins below deck and the passengers’ poisoning.

Both men will be remanded in custody on the charges of having committed a grave crime against public safety.

The Split-Dalmatia County police recalled that a yacht sailed into the port of Hvar on Tuesday, with a dead man aboard and five other persons in a serious condition who had to be taken to Split and hospitalised there. Three of those five persons are aged 64, 56 and 44 and their condition is stable, while two are children – aged 11 and 5 – and they are in a life-threatening condition. They are all Italian nationals.

The investigation into the case continues.