A Thai navy SEAL who took part in the dramatic rescue of 12 boys and their soccer coach from a flooded cave in Thailand last year has died.

His death is related to a blood infection he contracted during the rescue operation.

The Royal Thai Navy said in a statement on Friday that Petty Officer Beiret Bureerak had been receiving treatment, but his condition worsened.

He spent the last year and a half fighting off the infection, since his heroic efforts to help rescue the boys and their coach.

Wild Boars Academy's coach Ekapol Chanthawong and 12 boys had gone to explore the Tham Luang caves in Chiang Rai province on June 23, 2018, when a rainy season downpour flooded the cave system and left them trapped underground.

They survived for nine days, drinking water dripping from rocks, before they were discovered and a rescue operation began.

The operation, which got worldwide attention, ended on July 10, when all the boys and their coach were brought out safely.

Petty Officer Beiret Bureerak, one of the Thai Navy Seals who saved the boys and their coach, has died from a blood infection he contracted during the operation. Photo / Facebook

Nineteen divers helped to escort the final members from the cave.

The Thai cave reopened last month.

Officials from the Tham Luang National Park said more than 2000 tourists arrived at the park to be among the very first to see the Tham Luang cave as it reopened.

This year it was revealed that in order to remove the boys from the cave safely, they were drugged with ketamine and handcuffed.

"To calm nerves, the parents were told the boys were being taught how to dive and the media reported that each of them would be tethered to an air hose and then swim out with one rescue diver in front and another behind. This was untrue," ABC Australia Southeast Asia correspondent Liam Cochrane wrote in his book The Cave.

"Those who had been inside the flooded tunnels knew there was no way a child who had never dived before could make it through the muddy and treacherous obstacle course.

"The only hope was to sedate them, put oxygen-fed masks with silicone seals over their faces and let the expert cave divers carry them out," Cochrane added.

"But it was crucial that the masks fitted tightly, otherwise they might drown."