A Turkish government inquiry into Israel's raid on a Gaza-bound flotilla that killed eight Turks and a Turkish-American says Israeli soldiers shot five victims at close range.

Turkey released details of its formal inquiry into the May 31 incident Friday, hours after submitting the report to a United Nations panel investigating the incident. Eight Turkish citizens and a Turkish-American were killed when Israeli commandos boarded the Turkish ship, Mavi Marmara.

Israel has insisted its soldiers acted in self-defense after being attacked by activists on board. An Israeli inquiry into the raid last month cleared the military and government of any wrongdoing and said that the armed defense of Israel's maritime blockade of the Hamas-ruled coastal strip was justified under international law.

The Turkish inquiry report - a summary of which was released to journalists Friday - concluded that Israeli soldiers used excessive, indiscriminate and disproportionate force on unarmed civilians. It said the raid was a blatant violation of international laws.

Open gallery view Pro-Palestinian activists on board the Turkish ship Mavi Marmara. Credit: Reuters

"The force used was not justified, it was excessive," committee member Mithat Rende, a Foreign Ministry official, told reporters.

The report said Israeli soldiers fired live bullets from helicopters, killing two of the activists, even before they had rappelled on board. Five of the victims were killed from close range, it added.

Furkan Dogan, the 19-year-old Turkish-American, was lying wounded after being shot in the leg when he was kicked by two soldiers, who then shot him from close range execution-style, according to the summary.

Another activist, Cevdet Kiliclar, was killed with laser-guided weapons while taking photographs, the report said.

The commando raid sparked a wave of condemnation worldwide and lead to an easing of Israel's blockade on the coastal territory. It further damaged already strained relations with Turkey, formerly one of Israel's closest allies in the region. Turkey recalled its ambassador to Israel and is demanding an apology and compensation for the victims before it says ties can return to normal.

In Jerusalem, Israeli foreign ministry spokesman Yigal Palmor said he could not comment on the Turkish findings because he had not seen the report.

A report published last month after an internal investigation in Israel found that the Israeli soldiers who took part in the raid had acted in self-defense. It also determined that Israel's three-and-a-half year blockade of the Gaza Strip does not break international law.

Palmor said Israel had submitted its own report to the UN and was waiting to hear what lessons could be learned so this doesn't happen again.

Rende said Turkish investigators questioned more than 100 Turkish and foreign activists on board the flotilla in compiling the report, and also sought the opinions of international legal experts.

"Israel violated laws regarding the safety of navigation in open waters and the freedom to navigate," Rende said, adding that the blockade of Gaza amounted to illegal collective punishment of 1.5 million people.

"Israel is responsible for the compensation of all damages and has to apologize," he said.

"The Israeli forces carried out a well-planned and fully equipped attack, with the use of a special combat unit, kitted with frigates, helicopters, zodiacs, submarines, automatic weapons, laser-guided weapons, and modified paintball guns," the Turkish inquiry read.

Rende said the excessive force caused panic among the activists forcing them to use their right to self-defense, even without firearms.