Prosecutors leveled involuntary manslaughter charges against a cruise boat captain and his assistant after their vessel capsized off Bahrain's coast last week, killing 58 people, officials said Tuesday.

They also said the owner of the boat, Abdullah al-Kobaisi, had been ordered held amid allegations that he ordered the vessel to sail even though it was reportedly unsteady and was not properly licensed.

The Al-Dana — a traditional dhow vessel refitted as a pleasure boat — overturned Thursday night as it made a sharp turn with around 130 people on board, mostly Indian and British employees of a South Africa-based company and its partners celebrating construction of Bahrain's World Trade Center.

Survivors have said the boat was swaying precariously even before it left the dock in Manama, and that more than a dozen passengers left because of worries over its stability. The prosecutor said Tuesday that the captain and the party organizer contacted al-Kobaisi and warned him about the situation, but he ordered the boat to sail.

The prosecutors said in a statement that the captain and assistant did not have sailing licenses. They were ordered held for at least seven more days.

Al-Kobaisi had applied for a license to use the boat for cruises, but had not yet met the requirements, according to the statement. The coast guard "had not issued him a coastal transport license, and he organized the ill-fated cruise without license," the statement said.

The prosecutor appointed a commission to examine the Al-Dana and determine its suitability for carrying passengers and its maximum capacity. The statement did not say whether the boat was overloaded.

Party organizers told al-Kobaisi before the trip that up to 150 people would be attending, and al-Kobaisi assured them that the boat could take up to 200 people, the prosecutor said.

Waters were calm as the Al-Dana launched its cruise, survivors have said. But as the boat was swaying even before setting sail, organizers asked some people to stay below deck to maintain the ship's balance. After the partygoers ate dinner, the boat turned to head back to shore and listed sharply, sending people and chairs on the upper deck sliding into the water. Then the boat overturned completely, trapping dozens below deck, survivors said.