Israeli Prime Minister Benjamin Netanyahu testifies Monday at an inquiry into the bloodshed aboard a Turkish ship that was part of a flotilla that tried to break an Israeli blockade to deliver aid to Gaza in May 2010. (Ronen Zvulun/Associated Press)

Israeli Prime Minister Benjamin Netanyahu testified in Jerusalem on Monday before an inquiry into a deadly raid on a flotilla of aid ships headed to Gaza earlier this year.

Netanyahu was the first witness in the government-appointed commission, which is investigating the events of May 31, when Israeli soldiers boarded one of six vessels in international waters and killed nine Turkish activists.

The Gaza-bound ships were trying to break through an Israeli naval blockade that has been in place since 2007, when the militant group Hamas assumed control of the Palestinian territory.

Israel maintains the raid was provoked and that its soldiers acted in self-defence. The incident sparked a diplomatic crisis between Israel and Turkey as well as protests around the world.

Journalists were restricted from using recording devices during Netanyahu's testimony, but according to a CBC reporter on the scene, Irris Makler, his message was a reiteration of Israel's position. Netanyahu told the panel that Israeli authorities tried to re-route the flotilla to deliver its goods via land, and that the naval blockade was both legal and necessary.

Despite this being a public commission, Makler said, the Israeli leader opted to give evidence behind closed doors to a restricted audience.

The inquiry has been criticized for being too limited. None of the soldiers or activists involved are to be interviewed, but several other Israeli politicians are set to testify.

The five-member commission is headed by a retired Israeli Supreme Court justice and includes two foreign observers, including Canadian Ken Watkin, a former judge advocate general of the Canadian Forces.

Although the commission does not have the power to mete out punishment, its findings could be politically damaging to Netanyahu and others at the top.

After testifying, Netanyahu again defended Israel's actions.

"It will be clear beyond any doubt that the state of Israel acted according to international law, that the [Israel Defence Forces] operated according to international law, according to the highest standards of the international community," he told reporters in Jerusalem.

Israel's defence minister and military chief of staff will also face the commission.

The United Nations has announced its own inquiries into the incident.

with files from The Associated Press