Turkey called on Tuesday for Israel to be punished for storming a Turkish aid ship bound for Gaza in an attack that left nine dead and Israel increasingly isolated in the face of international outrage.

Israel detained or deported hundreds of activists who were aboard a flotilla of ships seized en route to the Palestinian enclave which has been under Israeli blockade since 2006.

Turkish Prime Minister Tayyip Erdogan urged the immediate lifting of "the inhumane embargo on Gaza", and Cairo announced the opening of its often-shut border with the territory, that is run by Islamist Hamas, an offshoot of Egypt's main opposition.

The United Nations called for an impartial investigation of the deaths of the nine people, four of them Turks, in the takeover by naval commandos who encountered violent resistance.

"Israel's behaviour should definitely, definitely be punished," a visibly angry Erdogan told a meeting of his parliamentary deputies, adding: "The time has come for the international community to say 'enough'."

Erdogan's Islamist views and outreach to Iran and Israeli enemies are blamed by many in Israel for souring ties between the Jewish state and Turkey, once its closest Muslim ally.

The bloodshed also put Israeli Prime Minister Benjamin Netanyahu's tense ties with U.S. President Barack Obama under further strain. Netanyahu cancelled talks with Obama to fly home from Canada to deal with the crisis.

A formal statement agreed by the U.N. Security Council drew a sharp response from Israel, which said its foreign minister complained in a telephone call with U.N. Secretary-General Ban Ki-moon that it was condemned unfairly for "defensive actions".

At the Gaza frontier town of Rafah, dozens of people raced for the Egyptian border after Egypt, like Turkey a leading Muslim nation in the region, said it would be opened "for an unlimited time" to allow Palestinians and aid to cross.

The move was asked for by Hamas. Cairo, coordinating with Israel, has opened the border only sparingly since Hamas seized control of Gaza in 2007.

While Israel grappled with world criticism, its navy said it was ready to intercept another aid vessel that organisers of the flotilla planned to dispatch to the Gaza Strip next week.

Big questions were unanswered: how far Israel could continue to blockade 1.5 million Palestinians in the Gaza Strip after condemnation from allies, and how it misjudged the situation and dropped marines onto a Turkish ship where they felt they had to open fire to save their lives.

As the first pictures emerged of a handful of Israeli marines being beaten and clubbed by dozens of activists, it was clear there would be anger in Israel over the mishandling.

HELD INCOMMUNICADO

Activists were held incommunicado by Israel but their accounts began to emerge after some were deported.

"We did not resist at all, we couldn't even if we had wanted to. What could we have done against the commandos who climbed aboard?" said Mihalis Grigoropoulos, who was aboard a vessel behind the Mavi Marmara, the cruise ship on which most of the violence occurred.

"The only thing some people tried was to delay them from getting to the bridge, forming a human shield. They were fired upon with plastic bullets and were stunned with electric devices," Grigoropoulos told NET TV at Athens airport.

Netanyahu was to convene his security cabinet to discuss the fallout from what Israeli newspapers termed a blundered raid.

Government sources said the ministers would consider whether to allow detained Turkish activists to return home on two planes that Turkey dispatched to Israel.

Obama, who has succeeded in reviving Israeli-Palestinian peace negotiations through U.S.-mediated indirect talks, said he wanted the full facts soon and regretted the loss of life.

After more than 10 hours of closed-door talks that gave rise to conflicting interpretations, the U.N. Security Council called for "a prompt, impartial, credible and transparent investigation conforming to international standards".

It also condemned "those acts which resulted in the loss of ... civilians and many wounded".

The use of the word "acts" instead of "act" -- the term preferred by Turkey -- suggested that activists who attacked the Israeli boarding party also bore some responsibility.

Marine commandos involved in the attack pointed to a failure of intelligence.

"We did not expect such resistance from the group's activists as we were talking about a humanitarian aid group," the boarding party's commander, an unnamed naval lieutenant who received special permission to be interviewed, told Army Radio.

"The outcome was different to what we thought, but I must say that this was mainly because of the inappropriate behaviour of the adversary we encountered."

Some 700 activists were processed in and around Israel's port of Ashdod, where the six ships of the blockade-running convoy had been escorted.

Among the activists were many Turks but they also included Israelis and Palestinians as well as Americans and many Europeans -- among them politicians -- and a Swedish author.

The military said the nine were killed when commandos, who stormed the Mavi Marmara from dinghies and helicopters, opened fire in what Netanyahu said was self-defence.

The Interior Ministry said on Tuesday that 50 activists had been taken to Ben-Gurion Airport for voluntary repatriation. Around 629 had refused, and would be held while Israel weighed its legal options. Some 30 were in hospitals with injuries.

Israeli Internal Security Minister Yitzhak Aharonovitch said police were gathering evidence to prosecute activists who had set upon the marines with fists, batons, knives and gunfire.

"All those who lifted a hand against a soldier will be punished to the full extent of the law," he told Israel Radio.

The European Union, a main aid donor to the Palestinians, and Russia demanded an inquiry and an end to the embargo. Netanyahu voiced regret at the deaths but vowed to maintain the blockade to stop arms smuggling by Iranian-backed Hamas.

Western-backed Palestinian President Mahmoud Abbas -- no friend of Hamas which seized the Gaza Strip from his Fatah faction in 2007 -- called the Israeli operation a "massacre".