Thai emergency personnel transfer a passenger from the sunken tourist boat at the Chalong pier in Phuket on Friday, as rescue operations continue for missing tourists following a boating accident late on Thursday afternoon. AFP / RASFAN

Rescuers in Thailand deployed helicopters and divers on Friday to search for survivors after two boats with a total of 127 Chinese tourists on board capsized in a storm off the country's southern resort island of Phuket on late Thursday afternoon.

At least 16 Chinese tourists died in the accident, 33 others were missing and the remaining 78 Chinese travelers had been rescued, according to the Chinese embassy in Thailand.

Norraphat Plodthong, the governor of Thailand's Phuket province, put the death toll at 33 and said 23 others were still missing as of Friday night, without clarifying how many of those were Chinese.

President Xi Jinping called for all-out efforts from the Chinese Foreign Ministry and the embassy and consulates in Thailand, as well as the Thai government and related authorities, to search for and rescue the missing Chinese and treat the injured.

He also called for more timely risk warnings for tourists during summer,when many people travel and flooding and rain are more common.

Premier Li Keqiang also urged more efforts to protect the safety of Chinese traveling abroad and to safeguard the legitimate rights and interests of Chinese citizens.

Thailand Prime Minister Prayuth Chan-ocha expressed his condolences on Friday to the families of those who died in the accident, and said the government will "exert all efforts to find those still missing and provide support to all survivors of this tragic event", The Associated Press reported.

A joint work team composed of officials from the Chinese Foreign Ministry, the Ministry of Transport and the Ministry of Culture and Tourism was heading to Phuket. A team of 10 Chinese rescuers, with light diving equipment, was to arrive in Phuket on Saturday morning to participate in the rescue work, according to the Ministry of Transport.

"What is imperative is to search for the missing," said a statement on Friday from the Chinese embassy in Thailand. "We ask the Thai side to mobilize all possible forces and waste no time in searching for the Chinese citizens who are still missing."

Most of the Chinese tourists involved in the accident were individual travelers who had ordered a one-day local tour. They came from provinces such as Jiangsu, Zhejiang, Guangdong, Liaoning and Henan, according to the Chinese Ministry of Culture and Tourism.

The government of Haining, Zhejiang province, confirmed on Friday that atotal of 37 people, including employees and their family members, from a furniture company in the city were involved in the tragedy. As of Friday night, 18 of them were missing.

The city established a team on Friday to help the victims' relatives to deal with visa-related affairs.

Helicopters scanned the water on Friday as divers tried to reach the boat, which the Thai Navy said had sunk to 40 meters below the surface of the Andaman Sea, a few kilometers off the coast of Koh He, an islet known for its coral formations and popular with day-trippers from Phuket.

The three-deck Phoenix was carrying 105 passengers, including 93 Chinese tourists, as well as 12 Thai crew members and tour guides, when it hit trouble and capsized around 5:45 pm, sparking a rescue attempt that took place in the dark.

Another boat, the Senereta, also overturned off Phuket during the stormy conditions on Thursday, but all 42 on board, the majority of them Chinese tourists, were rescued.

The captain of the Phoenix told China Central Television that some garbage was caught in the drainage system, causing it to malfunction. The hull was unstable, and then several strong waves hit it. The ship began to tilt and finally capsized.

The boat, which went down about 7 km from shore, was properly registered and had not been overloaded, local police said.

On Friday, local television broadcast images of dozens of divers searching for the missing, while more rescuers were on standby at a nearby pier. The seas were calm and the skies were clear, according to a Reuters report.

"Right now, officials from the Marine Police and Navy are helping to dive at the spot where the boat sank," the Thai Marine Police said in a statement. "They are diving to a depth of about 40 meters."

A Marine Department official said there was probably "no chance" that any more survivors would be found inside the boat, the Reuters report said.

"A day and a night has passed," said the department's deputy director-general, Kritpetch Chaichuay.

Ni Minghao, a 38-year-old Chinese who runs a travel agency in Phuket, said many volunteers from local travel agencies who speak both Chinese and Thai have participated in the rescue and treatment work, offering translation services in hospitals where the Chinese survivors and the injured were receiving medical treatment.

Rescuers dive to 40 meters below the surface where the  Phoenix sank on Thursday off Phuket Island after a violent storm struck. XINHUA

Dreadful memory

Wang Xiyu, 19, from Tonghua, Jilin province, who also went out to sea on a boat in Phuket and returned safely on Thursday at around 7 pm, described her experience as a "disaster".

Wang, with another four friends traveling to the island for holiday, bought a one-day sail trip for about 300 yuan ($45) on Wednesday through an online travel agency.

She witnessed the capsizing of the two boats, saying the storm created waves more than 4 meters high and caused great fear and desperation.

"I thought I would be over, especially after I saw one of the boats next to ours was almost perpendicular to the sea and some tourists on that boat were swallowed by the heavy waves," she said.

"The weather was good when we were on our way back to the Phuket Island from Racha Island at the beginning. I was fishing, chatting and laughing with my friends,"Wang recalled. "None of us knew we would experience such a storm the next minute."

"Our laughter suddenly stopped. We looked at each other in panic and kept silent," she said, adding that she did not receive any advance warning of the stormy, windy conditions from the local meteorological department or the agency.

Wang, who had arrived in Phuket on Tuesday, said she would continue her holiday in other places in Thailand in the following days, but "just won't sail anymore".

Weather warning

Thailand is in the middle of its rainy season, which usually runs from May to October and often generates high winds and flash storms in coastal areas, especially on its west coast on the Indian Ocean, where Phuket is located.

The Phoenix was among several boats that appeared to have ignored a warning in place since Wednesday not to take tourists on day trips to the islands that dot the seas off Phuket, Agence France-Presse reported.

Several other vessels hit trouble late on Thursday, but all of their passengers were rescued.

Ni, the Phuket travel agency operator, said the island's meteorological department issued a weather warning earlier this week that said the weather would turn bad starting on Thursday and might bring waves of 2 or 3 meters high, and suggesting that local travel agencies and boat companies not leave the docks.

He said he was not sure whether the alert was sent to all sailing service providers, but he added that his agency canceled all sailing trips due to safety concerns.

Ma Zhenhuan in Haining, Zhejiang, and Mo Jingxi in Beijing contributed to this story.