Former New Zealand Prime Minister Sir Geoffrey Palmer says heading an inquiry into the fatal Israeli raid on the Gaza-bound aid flotilla earlier this year is probably the hardest job he has ever done.
"I can't think of a harder one that I've had," he said.
"I think it's the inherent complexity of it, that's the problem."
Nine pro-Palestinian activists were killed when Israeli marines stormed a Turkish ship in May as a flotilla moved to breach the blockade to supply aid to residents in Gaza.
New Zealander Nicola Enchmarch was among the passengers and crew who were captured and detained in Israeli custody before being deported.
Overnight United Nations chief Ban Ki-moon announced the four-member panel, to be chaired by Sir Geoffrey with outgoing Colombian President Alvaro Uribe as vice-chairman, plus one Israeli and one Turkish member.
The identities of the members from Turkey and Israel have not been given, but the panel is due to begin work on August 10 and submit a first progress report by mid-September.
Sir Geoffrey said the inquiry could take as long as six months. It would be based in New York and he could not say if visits to the Middle East would be required.
In fact he could not give any detail about procedures or substance of the inquiry: "It's so sensitive and it's necessary to have a degree of detachment here to avoid arriving at any conclusions about anything for the moment".
He would head over to New York this week.
Sir Geoffrey said he felt honoured by the appointment.
"It is some sort of recognition that New Zealand can play a useful role in this sort of thing and I think that's good."
His family was "fine" with his involvement and he declined to comment on whether he may become a target.
"I don't think security matters should ever be discussed."
Israel's decision to back the panel was unexpected as it had for weeks insisted it would not cooperate with any international probe and instead launched two internal inquiries.
In the end following contacts and consultations with a seven-member Israeli ministerial forum Israeli Prime Minister Benjamin Netanyahu agreed, saying his country had nothing to hide.
Sir Geoffrey said that was an achievement for Mr Ban: "Diplomacy is the art of the possible and he's brought it off".
Foreign Minister Murray McCully welcomed the news.
"Sir Geoffrey has had a long and distinguished career, and his recent work as New Zealand's Whaling Commissioner has demonstrated his standing in the world of international law and diplomacy," he said.
"Sir Geoffrey has been appointed personally by the Secretary-General after extensive consultation with representatives of Israel and Turkey."
Sir Geoffrey said the Government had been supportive since Mr Ban approached him first about two months ago.
"Although the New Zealand Government has no responsibility for this inquiry they did support me, the Minister of Foreign Affairs and his staff.
Jim McLay New Zealand's next Permanent Representative to the United Nations, kept Sir Geoffrey up-to-date - sometimes ringing in the middle of the night his time.
"I was extremely grateful for the facilitation they provided in all of that."
In June when Sir Geoffrey's involvement was first suggested Prime Minister John Key said New Zealand supported an international investigation led by the UN and Sir Geoffrey would do a good job.
"He's a very, very intelligent man and has a great knowledge of the law and I think it is (also) a recognition that New Zealand is seen as an honest broker, we don't take sides between Palestine and Israel."