Israel is not co-operating with the UN Human Rights Council's probe of May's deadly raid on a Gaza-bound aid flotilla, and it's unclear if investigators will be able to speak with Israeli soldiers involved, a UN official says.

Juan Carlos Monge, a UN human rights officer working with the fact-finding mission, said Tuesday the panel was speaking with other witnesses and government officials in Turkey and Jordan.

But Israel hasn't granted an invitation to the team, which is examining whether Israeli commandos broke international law by killing nine pro-Palestinian activists trying to break the Jewish state's blockade of Gaza. Eight of the dead activists were Turks, and the ninth was Turkish-American. Israel says the soldiers acted in self defence.

Monge said in an email to The Associated Press that the mission would only speak with Israeli soldiers about the incident if permission is given by the Israeli government. Such approval is important to the investigation if it hopes to be objective, but Israel has refused to work with council probes in the past, citing their bias.

Israel's UN mission said Tuesday it will not comment on the investigation, but Israeli officials have suggested since the panel's creation in June that the Jewish state wouldn't co-operate. Israel considers the Human Rights Council to be anti-Israel, and points to a series of critical resolutions by the body in its four-year history.

Working with other UN group

Israel is working with a separate UN group — under New Zealand's ex-prime minister, Geoffrey Palmer, and Colombia's ex-president, Alvaro Uribe — that is also examining the incident, said Foreign Ministry spokesman Yigal Palmor.

But Palmor said the 47-nation rights council "deals obsessively and morbidly with Israel."

Former UN war crimes prosecutor Desmond de Silva, Trinidadian Judge Karl T. Hudson-Phillips and Malaysian women's rights advocate Mary Shanthi Dairiam are investigating on behalf of the rights council.

They will present their report to the council on Sept. 27.

The separate examination ordered by UN Secretary General Ban Ki-moon includes an Israeli and a Turkish representative on the panel, and both countries have pledged co-operation.