Ahmad Puzi Ab Kahar (Front), director general of Malaysian Maritime Enforcement Agency, briefs media on the rescue mission of the boat accident in Kota Kinabalu, Malaysia, on Jan 30, 2017.[Photo/Xinhua]

Related: Search continues for the missing in boat accident in Malaysia

KOTA KINABALU, Malaysia -- No new survivors of a boat carrying Chinese tourists sank off Malaysia's Sabah state were found Monday, while authorities have launched investigation into the accident, arresting the boat owner and two crew members.

Ahmad Puzi Ab Kahar, director general of Malaysian Maritime Enforcement Agency, told Xinhua via phone that no new survivors were found and the search and rescue would continue.

Speaking to a press conference, Ahmad Puzi said the search area had been expanded to 2,400 square nautical miles, involving assets from his agency as well as Malaysian navy and air force. Neighboring Brunei has sent aircraft to search its waters.

The search faces challenges caused by strong wind and rough sea, but "that were not the excuses and problem for us to continue the operations," he said.

Meanwhile, Malaysian authorities have started investigation into the accident. Prime Minister Najib Razak said on a social media posting that he saw the tragedy seriously and want a detailed investigation to find out the cause of the incident.

The skipper and the crewman were arrested for suspecting causing death by negligence, said Sabah police chief Ramli Din. The two crew members were the first to be rescued after their boat sank on Saturday on the way from the state capital Kota Kinabalu to Pulau Mengalum, a popular tourist island some 60 km to the west.

The owner was arrested later on Monday, and police has launched a full probe into the accident, including whether the boat was overloaded and whether it was operated with license and insurance, Ramli told Xinhua.

Sabah police chief Ramli Din (2nd L) briefs media on the investigation of the missing boat carrying Chinese tourists in Kota Kinabalu, Malaysia, on Jan 30, 2017.[Photo/Xinhua]

"We will investigate from all angles, pertaining to negligence if any," he said.

Ramli said the boat was carrying 27 Chinese tourists instead of 28 as reported earlier. One tourist was registered for the trip but cancelled the visit after seeing the boat was full.

That brings the number of unaccounted for down to five, including a crewman, not six as reported earlier, he said. China's Consulate General in Kota Kinabalu said the new figure would have to be verified.

The passengers and crew were left adrift at sea after the boat sank in rough sea, before 20 Chinese tourists were rescued Sunday. Three tourists were found dead.

The tourists were sent back to Kota Kinabalu early Monday and admitted to a hospital. All suffered from sunburn and dehydration but were in stable conditions, according to the hospital.

A Chinese tourist who went to Pulau Mengalum for snorkeling on Saturday recalled the bumpy trip in bad weather. "It almost broke my waist," she told Xinhua. She also recalled the crowded boat and the fact that many passengers were not wearing life jackets.