The incident, which occurred off Koh Tachai in the Similan Islands National Park, came just days after the death of an Indian tourist on his first dive off Koh Phi Phi. He had drowned after falling off his dive-boat, and two diving instructors have since been charged with negligence.

In the latest case of Yoshida Saori, 37, police told the Phuket News that while the three people had been charged with recklessness causing grievous bodily harm and death, further charges were being considered.

The Japanese diver was reported to have been on a “three-day beginner course” and had been on her first dive to 10m with three other trainees and the instructor.

The dive-boat had been drifting and the captain started the engine to manoeuvre it back into position.

Saori, who had become separated from her group, was struck by its propeller and suffered multiple deep lacerations to her right thigh and considerable blood loss.

After preliminary treatment she was conscious on her way to Phang Nga on the mainland, some 40 miles away, but pronounced dead after her arrival at a hospital there.

Police stated that the dive-tour operator, South Siam Divers, would not face any charges because it had not been directly involved in the incident. They also said that its insurance company was to pay 1 million baht (about £23,000) in compensation to Saori's family.

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