The investigation will be led by former New Zealand Prime Minister Geoffrey Palmer as chairman and outgoing Colombian President Alvaro Uribe as vice chairman, Ban said in a statement. The panel also will have one Israeli and one Turkish member, who were not identified.

The four-member group will start work on Aug. 10 and submit its first progress report by mid-September, Ban said.

The storming of the Turkish-owned flotilla, which was trying to run Israel's blockade of Hamas-ruled Gaza, caused an international outcry after Israeli commandos killed eight Turks and one Turkish-American.

The action led to a sharp deterioration in Israeli-Turkish relations and forced Israel to ease its Gaza blockade, which the Jewish state says aims to prevent Hamas from acquiring military capacity to attack Israel.

Ban's announcement came shortly after Israel, which has already completed its own military investigation and begun a civilian one, said it had decided to cooperate with Ban.

A statement from Prime Minister Benjamin Netanyahu's office said he had told Ban on Monday of his agreement "following diplomatic contacts over the past several weeks aimed at ensuring the panel and its mandate will be fair and balanced."

Turkey welcomed the announcement. "From the beginning, Turkey has demanded a UN-led international committee to investigate the raid ... As a result of Turkey's initiatives with the UN, the United States and Europe, Israel has agreed to cooperate with the committee," a government source said, speaking on condition of anonymity.

"This is a very important decision for Turkey," he added. "This committee is an important step in remedying the injustice Turkey has encountered in the raid."

Ban, in his statement, called the launch of the panel "an unprecedented development." He thanked the leaders of two countries he had consulted with during the weekend — an apparent reference to Israel and Turkey — "for their spirit of compromise and forward-looking cooperation."

He said the panel would give recommendations for preventing future incidents and hoped the agreement to open the inquiry would help Turkish-Israeli ties.