An Australian doctor is at the centre of the desperate attempt to rescue 12 Thai boys and their soccer coach trapped in a cave in Chiang Rai.

Richard Harris, an anaesthetist from Adelaide, has been revealed as one of the international dive experts seconded to assist with the difficult and dangerous rescue mission.

Australian doctor Richard Harris (in light blue shirt) at the base camp where the rescue operations are now under way. Credit:Kate Geraghty

On Saturday, Dr Harris undertook the dangerous dive through to the 12 Thai boys and their coach.

He gave the final approval on the boys' health, clearing the way for the rescue attempt which commenced on Sunday.