Israel's navy boarded another aid ship on Saturday to enforce a blockade of Gaza five days after its troops killed nine people on a Turkish aid boat, despite Washington saying the policy was 'unsustainable.'

The Israeli navy, whose action on Monday triggered an international outcry, took control of the Rachel Corrie without incident, the Israeli military said.

The boat had ignored Israeli orders to divert to Israel's Ashdod port where Israel had offered to unload the cargo and deliver it to Gaza after inspecting it.

'According to initial reports, there was no violence or injuries amongst the soldiers or the crew, as the use of force was unnecessary and no shots were fired,' the Israeli military said in a statement.

Israeli Prime Minister Benjamin Netanyahu issued a statement saying: 'Forces used the same procedures for Monday's flotilla and Saturday's sailing but was met by a different response.

'On today's ship and in five of the six vessels in the previous flotilla, (their boarding) procedure ended without casualties. The only difference was with one ship where extremist Islamic activists, supporters of terrorism, waited for our troops on the deck with axes and knives.'

Carrying Irish and other activists, the ship was the latest to attempt to break the four-year old blockade imposed by Israel on Gaza with the stated aim of stopping its Hamas rulers from strengthening their arsenal to fight the Jewish state.

'Israel will continue to exercise its right to self defence. We will not allow the establishment of an Iranian port in Gaza,' Netanyahu's statement added.

'This has been another brazen act of Israeli piracy on the High Seas,' said Kevin Squires, national coordinator of the Ireland Palestine Solidarity Campaign in Dublin, one of whose members was aboard the boat named after a pro-Palestinian activist killed in Gaza in 2003.

Autopsy results found 30 bullets in the bodies of the activists killed this week, a British newspaper reported.

They were all Turks, including one with US citizenship. Ankara's already strained ties with Israel, once an ally, are at an all-time low.

In the clearest sign yet that this week's bloodshed might lead to a modification of the blockade, the United States said the embargo was 'unsustainable and must be changed.'

Israel stops cement and other materials it says could be used by Hamas for military purposes from entering the territory controlled by the group since 2007. It also stops other goods with no obvious military application.

Hamas, an Islamist group backed by Syria and Iran, is hostile to Israel and does not recognize interim peace agreements signed by the Western-backed Palestinian Authority led by President Mahmoud Abbas.

Friends and foes alike have heaped criticism on Israel this week over the blockade. Israel's main ally, the United States, has expressed more sympathy than most for its security concerns but has also spoken of the need for Palestinians in Gaza to receive adequate supplies.

'We are working urgently with Israel, the Palestinian Authority, and other international partners to develop new procedures for delivering more goods and assistance to Gaza,' a spokesman for the White House National Security Council said.

'The current arrangements are unsustainable and must be changed. For now, we call on all parties to join us in encouraging responsible decisions by all sides to avoid any unnecessary confrontations,' he added in a statement.

U.N. High Commissioner for Human Rights Navi Pillay increased the pressure on Israel, saying the embargo, which has blighted the lives of the 1.5 million people, was illegal and should be lifted.

'International humanitarian law prohibits starvation of civilians as a method of warfare and ... it is also prohibited to impose collective punishment on civilians,' she said.-Reuters