KOTA KINABALU, Malaysia, Feb. 2 (Xinhua) -- China's Consul-General in Sabah Chen Peijie on Thursday requested Malaysian authorities to consider the possibility of seeking victims of the sunken boat underwater, as the search operation enters into its sixth day.

During a discussion with First Admiral Adam Aziz, Kota Kinabalu director of the Malaysian Maritime Enforcement Agency, Chen said there may be a possibility that the victims' bodies were trapped by water plants, nets or shipwreck.

"Please check carefully and look carefully for every possibility," said Chen.

At a daily briefing held afterwards, Aziz said Thursday's search operation, involving 22 assets, will still focus on the 3,900 square nautical miles as it was Wednesday. He noted they will put their full efforts in the daytime because the weather will turn bad in the evening.

Aziz said because they did not know the exact position where the boat capsized, they can only comb through the much bigger area, where the water is almost 50 meters deep.

"Our normal divers can only go down up to 20 meters, so for 50 meters, we will try to get maybe ROVs, remotely operated vehicles," said Aziz, adding that they learned from the survivors that an old man may have sunk with the boat, but it is still yet to be confirmed.

The catamaran, carrying over two dozen Chinese tourists and three crew, went down in turbulent waters while heading for the popular island of Mengalum on Saturday. Twenty-two people have been rescued but three Chinese tourists have been confirmed dead. Another five Chinese tourists and a crew member are still missing.