Turkey says it has no trust in an inquiry being set up by Israel to investigate an Israeli military raid on a flotilla carrying aid to Gaza.
Nine Turkish nationals on board one of the vessels were killed in the assault.
Turkish Foreign Minister Ahmet Davutoglu says the investigation should be conducted with both Turkish and Israeli representatives.
"We have no trust at all that Israel, a country that has carried out such an attack on a civilian convoy in international waters, will conduct an impartial investigation," he says.
"To have a defendant acting simultaneously as both prosecutor and judge is not compatible with any principle of law."
Israel announced its plans to hold an inquiry - headed by a former Supreme Court judge and with two non-voting foreign observers - after earlier rejecting a UN proposal for an international inquiry.
Following an emergency session held after the raid on 31 May, the UN Security Council called for a "prompt, impartial, credible and transparent" investigation.
Palestinian leader Mahmoud Abbas also says the Israeli inquiry does not correspond to what the Security Council wants.