KUALA LUMPUR/BEIJING (REUTERS) - Malaysian rescuers on Sunday (Jan 29) found 23 Chinese tourists and two crew members alive after their boat sank in rough seas off the coast of Borneo a day earlier, but five Chinese tourists and one Malaysian crew member are still missing, officials said.

The boat, a catamaran, failed to arrive at popular tourist spot Mengalum island after departing Kota Kinabalu, the capital of the eastern Malaysian state of Sabah, on Saturday morning.

The Malaysian skipper, rescued along with a crew member at around 2pm (0600 GMT) on Sunday, told the authorities the boat sank after being damaged in turbulent waters. "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," Malaysian Maritime Enforcement Agency director-general Ahmad Puzi Ab Kahar told a news conference in Kota Kinabalu.

Ahmad Puzi said authorities were investigating the sinking of the catamaran and whether it should have been used as a tourist vessel. "We will deploy search assets that can operate at night, and continue our rescue operations to locate those who are still missing," Malaysia's National Security Minister Shahidan Kassim said. "The weather conditions were also quite bad with very high waves, which raises the question as to whether the boat should have gone out to sea," he said.

The Malaysian navy, maritime police and air force were involved in the search, which covered 400 nautical miles.

Chinese President Xi Jinping called on his country's government departments to step up cooperation with their Malaysian counterparts on rescue efforts, official state news agency Xinhua reported.

The China National Tourism Administration said it has initiated emergency response procedures.