Turkey will not normalize relations with Israel until Tel Aviv agrees to an international inquiry into the deadly attack on the Gaza-bound aid ships, a senior official says.

"If they do not agree to (an international inquiry), it would mean that there are certain facts they want to hide," Turkish Foreign Minister Ahmet Davutoglu said Monday.

If Israel continues to reject the inquiry, "normalization in relations would be out of the question," he was quoted as saying by AFP.

Last Monday, Israeli forces attacked the Gaza Freedom Flotilla, compromising six ships en route to the blockaded Gaza Strip, killing at least 20 activists, most of whom were Turkish.

The attack has strained already shaky ties between Ankara and Tel Aviv.

The UN Human Rights Council on Wednesday condemned Israel's "outrageous attack" on the ships and set up an independent international investigation into the incident.

Israel has resisted probe of the assault, with its ambassador to Washington Michael Oren saying Tel Aviv rejects "the idea of an international commission."

The Turkish foreign minister, meanwhile, questioned Israel's move to "intercept a civilian ship sailing in international waters."

The remarks come as a Eurasian security summit is scheduled to be held this week in the Turkish city of Istanbul.

The meeting is expected to address the Israeli attack on the aid activists. Israel, a member of the forum, is sending a consular level official rather than a high-ranking official to the summit.