Bangkok: Rescuers in Thailand deployed helicopters on Friday in a search for 29 people still missing after the sinking of a tourist boat off the island of Phuket, as the death toll in the incident rose to 27.

The Royal Thai Navy said ‘quite a few bodies’ were found in the vessel, the Phoenix, after it capsized and sank in rough seas on Thursday carrying 105 passengers, comprised of 93 Chinese tourists and 12 Thai crew and tourist guides.

Thai television broadcast images of dozens of divers, some carrying scuba gear, searching for missing passengers and crew at the scene, while more rescuers waited on standby at a pier nearby. Sea conditions were calm and skies were clear.

‘Right now officials from the marine police and navy are helping to dive at the spot where the boat sank,’ Thailand’s Marine Police said in a statement. ‘They are diving to a depth of about 40 metres (yards).’

Police are investigating the incident, the Phuket Marine Police said, adding that the boat was properly registered and had not been overloaded at the time of the accident.

It went down about 7 km (5 miles) from shore and had sunk to a depth of about 38 to 40 metres (yards), the Royal Thai Marine Corps said in a statement earlier.

Thailand is in the midst of its monsoon season, which usually runs from May to October, and often generates high winds and flash storms in coastal areas.

The Chinese embassy in Bangkok said it had requested the Thai government to make all-out rescue efforts, and had sent a team to Phuket to help.

In its statement, it added that the Chinese consulate in southern Thailand already had staffers on the scene helping its citizens.

Chinese tourists make up the biggest number of foreign visitors to Thailand, their numbers surging in recent years, drawn by the growing popularity of the southeast Asian nation’s islands.

In Beijing, a foreign ministry spokesman said China’s top leaders, including President Xi Jinping, were paying close attention to the incident.

‘China expresses gratitude for the active search and rescue efforts made by Thailand,’ the spokesman, Lu Kang, told a regular briefing.

Another boat sailing in the same area also capsized but all 35 tourists, five crew and a guide on board were rescued, the Water Safety Department of the Harbour Department said.

Thailand has a poor record on road and boat safety. Many tour operators have complained about lax enforcement of basic safety measures, such as seatbelts in cars and lifejackets on boats.

More than 20 people were killed when a tourist boat carrying 150 people capsized in Thailand’s ancient city of Ayutthaya in 2016. Officials blamed the accident on overcrowding and reckless piloting.