Thai divers have scoured the wreckage of a boat with Chinese tourists that sank in a storm off the resort island of Phuket, as the death toll rose to 33 with more than 20 others still missing, officials said.

Key points: The boat was one of three to encounter difficulties on the rough sea

The boat was one of three to encounter difficulties on the rough sea Police had issued a dangerous weather warning until next Tuesday

Police had issued a dangerous weather warning until next Tuesday Phuket officials are considering banning boats from going to sea in strong winds

Some of the bodies were found by divers who entered the wreck on Friday and others were floating in the water, navy official Narong Aurabhakdi said.

The Royal Thai Navy said "quite a few bodies" had been found inside the sunken vessel.

The boat was carrying 105 people, including 93 tourists, 11 crew and one tour guide when it toppled in five-metre-high waves on Thursday evening.

At least 12 of the injured were hospitalised.

The boat was one of three to encounter difficulties at sea in the area. ( AP )

Jin Yilin, consul-general of the Chinese Embassy in Thailand, said a delegation from the Chinese Foreign Ministry was on the way to Thailand.

The boat was one of three to encounter difficulties at sea in the area on Thursday, the navy said.

Another two boats, including a yacht carrying 39 people, also capsized but its passengers have been brought to safety.

Thai media showed photos of rescued people in large rubber life rafts at sea, with fishing boats and churning water in the background.

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The images also showed survivors being lifted from the rafts and sitting in life jackets amid ropes on the deck of what appears to be a fishing trawler.

Phuket officials had earlier issued a warning of severe weather until Tuesday, including heavy rain and winds.

"All agencies are co-operating in their search at this time," Phuket Governor Norraphat Plodthong said.

"We have given warnings … but the winds are strong."

Thailand is already making international headlines after 12 boys and their junior soccer coach were found alive this week after becoming trapped inside a cave in the country's north.

Rescuers found the boys after 10 days and a multinational rescue operation to extract the boys is still ongoing.

Road and boat accidents involving tourists are common in Thailand, where safety standards are sometimes well below international norms.

AP/Reuters