Police are expanding their investigation into last Thursday's boat tragedy in Phuket where the death toll has risen to 45 with two people still missing, a senior police officer said.
Phuket provincial police chief, Pol Maj Gen Thirapol Thipcharoen, said the probe against TC Blue Dream and Lazy Cat Travel is to find out if these firms are running their businesses in compliance with the law and if their business operations meet required safety standards.
TC Blue Dream Ltd is linked to the Phoenix tour boat which had 89 mostly Chinese tourists on board while Lazy Cat Travel is associated with the yacht that sank the same day. All on board that vessel were rescued.
He said police have interviewed a number of witnesses including the bosses of both firms and will examine both boats as part of the investigation.
He said the probe will also determine if any other factors caused the Phoenix to capsize besides the storm.
If human error is involved, those responsible whether they be the tour operators or state officials in charge of safety operations, will face legal action, he said.
He said the Royal Thai Police (RTP) will decide whether to allow Chinese officials to join the investigation to ensure transparency.
The companies are also suspected of being owned by foreigners.
According to Pol Maj Gen Thirapol, no one has been arrested on suspicion of acting as a proxy for foreign interests, but three people have been arrested over the actual sinkings.
Two are the skippers of the Phoenix and the yacht. The other is a Chinese national described as being the manager of Lazy Cat Travel.
They face charges of recklessness causing deaths and injuries.
On Tuesday authorities raided 11 locations including TC Blue Dream and Lazy Cat Travel in Phuket suspected of having foreign owners and seized a number of documents for examination.
Deputy Tourist Bureau chief Surachate "Big Joke" Hakparn said Wednesday that the preliminary investigation has found irregularities indicating that the two companies involved in the boating accidents ran substandard tour operations and allegedly evaded customs taxes.
According to Pol Maj Gen Surachate, the raid teams found that life vests were not certified by the Thai Industrial Standard Institute and use of substandard equipment put tourists in danger.
Commenting on blueprints seized, he said the Phoenix was not built to standard requirements, which exposed the vessel to greater risks in stormy weather.
The boat was said to be poorly designed with inadequate emergency exits.
As of Wednesday night, local authorities had put the death toll at 45 with two people still missing.
Operations to retrieve a body trapped under the Phoenix continued to be hampered by rough seas and waves of three metres.
The body cannot be identified and remains on the list of missing tourists.
The operation to retrieve the body involved three vessels sent by the navy which were joined by one from Chinese firm, Guangzhou Salvage.
Phuket governor Norrapat Plodthong said the search for the missing would continue until all are accounted for.
He said any decision to end the operation would be jointly made by Thai and Chinese authorities.