The head of the Philippines air force says the string from a child's kite was responsible for a military helicopter crash that killed nine people.

Lieutenant General Horacio Tolentino says one of the crash survivors, Captain Allan Villagarcia, has told him the aircraft was flying perfectly and just about to land in the central island of Cebu when a kite got entangled in the rotor blades.

"There was no problem with the engine," he said. "It [the kite string] caused the stoppage of the rotor."

Lieutenant General Tolentino says Muslim rebels have used kites to disable air force helicopters in the past but terrorist involvement is not suspected in the latest incident.

He says the nylon kite string was found still entangled, just below the main rotor blade.

The Vietnam-era UH-1H "Huey" helicopter, carrying four people on a training flight, went down on a crowded street, killing seven people on the ground and two members of the crew.

Lieut Gen Tolentino says the kites were being flown in an area where kite flying is banned to avoid endangering aircraft, but the air force has no plans to charge anyone.

"We are not blaming anyone for what has happened," he said.

"It is not the intention of the people flying the kites to cause accidents."

The full report on the April 28 crash has not been released.