The UN Secretary General has insisted other nations should oversee an investigation into Israel's deadly boarding of a Turkish ship.
Ban Ki-Moon restated the demands days after Israel rejected a similar suggestion that the probe be carried out by an international tribunal.
Israel is insisting it should carry out the investigation itself.
Nine people died when Israel prevented a flotilla of ships docking in the Gaza Strip on 31 May.
Israel has outlined the focus of the probes it will conduct.
They will look exclusively into the legality of Israel's naval blockade of Gaza and the raid on the aid flotilla, Israeli minister without portfolio Benny Begin told public radio on Tuesday.
But a UN spokesman said Mr Ban still hoped for "credible international involvement" in the investigation to ensure it was "prompt, credible, impartial and transparent".
He said they had not received an official rejection from Israel.
On Sunday Israel's ambassador to the US, Michael Oren, told US broadcaster Fox News that Israel has the ability and the right to investigate its own military.
That came hours after Mr Ban had called the Israeli PM Benjamin Netanyahu to outline plans for an international tribunal.
At a regional security conference in Turkey on Tuesday 21 out of 22 member countries denounced the raid on the Turkish ship the Mavi Marmara.
Israel, also a member of Conference on Interaction and Confidence Building Measures in Asia, rejected criticism at the meeting.