Malaysian officials have expanded their search for a group of four Chinese tourists and a Malaysian who have been missing since their boat capsized during a Lunar New Year cruise Saturday.

Reuters reported three Chinese passengers were killed when the catamaran sank off the coast of Borneo.

The boat, which was carrying 27 Chinese tourists and three crew members and traveling from Kota Kinabalu to the tourist hotspot of Mengalum Island, was apparently battered by powerful waves.

The head of the Malaysian Maritime Enforcement Agency (MMEA) said the tourists were tied together by life jackets and taken away by the current. Fisherman managed to rescue 22 people, including the boat's captain.

"According to the skipper, the boat was 'broken' after being hit by strong waves, and sank. All the tourists were tied together and were carried away by the currents," the MMEA's director-general Ahmad Puzi Ab Kahar told reporters Sunday via Reuters.

Ships and aircraft are currently searching 2,400 square nautical miles of sea but have been slowed down by strong winds and rough waters.

The boat's captain, owner and one other person were arrested for questioning.

In a statement, Malaysian Prime Minister Najib Razak said "at the moment we must concentrate fully on the search and rescue efforts." But he's also requested a full investigation into why the boat sank.

One of the questions being asked is whether the boat was fit to be used as a tourist vessel.

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