Window falls from US Marines helicopter onto school grounds in Japan amid row over safety fears

A schoolboy was left injured after a window fell from a military helicopter onto a school sports field near a US Marines air base in Japan.

The boy was among about 50 children on the elementary school grounds when the window fell from the CH-53E transport helicopter today.

Japan's central government and Okinawa authorities have been at odds for years over the Futenma base.

Residents have repeatedly complained about what they see as the unfair burden they carry in supporting the US military presence in Japan.

The nature of the boy's injuries and exactly how they were sustained remain unclear.

Japan's Chief Cabinet Secretary Yoshihide Suga said: "This sort of incident creates anxiety not only among those involved with the school but the people of Okinawa and should never happen."

The U.S. Marines on Okinawa said in a statement the helicopter had immediately returned and reported the incident.

"We take this report extremely seriously and are investigating the cause of this incident in close coordination with local authorities," the statement said.

"This is a regrettable incident and we apologise for any anxiety it has caused the community," it said.

The Futenma base is surrounded by schools, hospitals and shops, and residents worry about air crashes. Crime committed by U.S. servicemen has also occasionally angered residents.

Okinawa Governor Takeshi Onaga has led the campaign to get the base off the island, while the central government has proposed moving it to a less populated part of the island called Henoko.