TOKYO - A JAPANESE woman playing golf with her family died in a freak accident when the greens under her feet collapsed and she plunged into a five metre deep cavern, police said on Friday.

A golf course official said the hollow space just below the lawn may have been formed by springtime mountain snow melt flowing through soils below the golf course fairway on Japan's far-northern island of Hokkaido.

Local authorities were investigating Thursday's deadly accident, which happened as the woman was playing golf with her husband and two children.

'We heard from firefighters that ... all of a sudden she fell into the hole in front of her 10-year-old son,' a local police official told AFP.

The woman, Takae Gassho, 38, from Sapporo, was dead when emergency officials pulled her from the hole at the Le Petaw Golf Club, which had only reopened the previous weekend after the winter season.

Officials believed she may have lost consciousness in the fall and then drowned in a puddle of water at the bottom of the cavern, where the hole was more than three metres wide, reports said.

A Hokkaido Golf Association official said that 'normally golf clubs conduct visual check-ups every day' but that 'nobody could have noticed that a hollow space was quietly forming underground'. -- AFP