State health officials said they were contacted yesterday to run laboratory tests for Norwegian Cruise Lines to determine what sickened more than 400 of the 2,500 passengers aboard the Pride of Hawaii.

The tests would confirm what caused the flu-like symptoms suffered by the passengers, officials said.

The federal Food and Drug Administration was in charge of the investigation of the outbreak, a state Health Department spokesman said.

The afflicted passengers on the interisland cruise ship fell ill after the vessel left Honolulu Harbor on Monday.

The vessel arrived at Maui yesterday and was expected to continue on to Kaua'i.

Passengers suffering from nausea, vomiting and diarrhea and their cabinmates were asked to remain quarantined in their rooms for 24 hours.

NCL said it was giving those passengers a $200 on-ship credit.

The company reported yesterday that the outbreak had been confined to just the one ship, and that the "Pride of Aloha" and "Pride of America" were not affected.

Passengers booked on the Pride of Hawaii's next cruise were informed of the outbreak to give them the option of not sailing, NCL said.