Tokyo - A disc-shaped piece of ice of unknown origin plummeted from the sky onto a golf course near Tokyo Wednesday, narrowly missing players on the fairway but causing no injuries, police said.

Authorities were investigating the bizarre incident, said Saitama prefectural (state) police spokesman Masahiko Kuwashima.

Four players at the Heisei Club golf course in Saitama, just outside Tokyo, heard a loud thud and found a disc-shaped hunk of ice - about 50 centimeters (20 inches) in diameter and 15 centimeters (6 inches) thick - broken into several pieces, Kuwashima said.

He said police investigators have asked the Transport Ministry to check a possibility that ice stuck on an airplane might have fallen, and are waiting for the ministry's response.

There have been several past reports of ice falling in Chiba prefecture (state) near Tokyo's Narita International Airport, Kuwashima said.

But there is no airport in Saitama, and the golf course involved Wednesday is not known to be beneath a flight route, he said.

No one has claimed responsibility for the mysterious incident, Kuwashima said.

"It's puzzling," he said, adding that the ice, which weighs 2 kilograms (4.4 pounds), was being kept in a police department freezer.