Demonstrators chant slogans as they welcome activists returning from Israel at the airport in Istanbul, Turkey, early Thursday. (Vadim Ghirda/Associated Press)

Thousands cheered the return of hundreds of activists who arrived by plane in Turkey and Greece early Thursday after being deported from Israel following Monday's raid on a Gaza-bound aid flotilla.

Most of those returning were Turkish and were greeted at the airport by Turkey's Deputy Prime Minister Bulent Arinc and several Turkish lawmakers.

"They faced barbarism and oppression but returned with pride," Arinc said.

A few thousand jubilant relatives and supporters, waving Palestinian and Turkish flags, burst into applause outside the airport, chanting "God is Great," The Associated Press reported. They later walked to the perimeters near the tarmac to see their loved ones. Another crowd celebrated their return in downtown Istanbul.

Turkey's prime minister has accused Israel of a "bloody massacre" and officials in Turkey have called for an international investigation of the raid.

Meanwhile, a Greek plane carrying 35 activists landed at a military airport near Athens as more than 100 relatives and supporters cheered and shouted pro-Palestinian slogans.

Seven planes had been used to deport 527 activists, Israeli Interior Ministry spokeswoman Sabine Haddad said. Seven other activists remained in Israeli hospitals for treatment of wounds suffered during the Israeli raid, she said.

The Israeli Foreign Ministry said three activists from Ireland, Australia and Italy remained in detention over "documentation and other issues," without elaborating.

At least nine people were killed when six ships trying to break the three-year blockade of Gaza were raided by Israeli commandos early Monday. The bodies of the nine were on the first plane.

Others activists were from Arab countries, Europe and the United States. Three Canadian activists were also deported.

Israel had said it will not prosecute dozens of activists detained in the raid, opting instead to deport them all immediately in an apparent effort to limit the diplomatic damage from the raid.

"Keeping them here would do more damage to the country's vital interests than good," Attorney General Yehuda Weinstein wrote in the order.

"We will never apologize for defending ourselves." Israeli Prime Minister Benjamin Netanyahu said earlier, adding Israel regrets the loss of life, but added,

At a news conference in Jerusalem on Wednesday, Netanyahu responded to international condemnation of the raid.

The raid prompted international criticism and fresh calls to lift the blockade of Gaza, although the details of what happened during the military raid are still not entirely clear.

Israeli soldiers had no choice but to respond with force and other countries of the world, under similar circumstances, would do the same, Netanyahu said.

"The way we exercise [our right to defend ourselves] under these conditions of duress, under the rocketing of our cities and under the impending killing of our soldiers, you know that we exercise it in a way that is commensurate with any leaders," he said.

Netanyahu said he has spoken with world leaders about the issue.

"I say the same thing to the international community: What will you do? How would you stop thousands of rockets that are destined to attack your cities, your civilians, your children? How would your soldiers behave under similar circumstances? I think that in your hearts you all know the truth."

Meanwhile, a Canadian citizen alleged he was detained and beaten during the raid.

While Netanyahu said his soldiers acted in self-defence after meeting violent resistance, Rifat Audeh, told CBC News the activists were unarmed civilians.

Rifat Audeh (Submitted photo)

Israel has said the activists were armed with metal rods, knives, slingshots and two pistols snatched from the troops. Israel has defended its military action and said the blockade is necessary for its security.

Audeh, who says he was aboard one of the ships, told CBC News that Israeli troops beat him when they boarded the ship and bound his hands.

"They beat me actually, the Israeli soldiers beat me on the ship," said Audeh, who has been released and sent to Jordan.

"We were detained for an extensive period of time and were not allowed to go to the washrooms or anything like that, or sleep," Audeh said. "It's been a rough 24 to 48 hours, let's put it that way."

Audeh is one of three Canadians who were detained during the raid, according to reports.

Media watchdog Reporters Without Borders said at least 60 journalists were accompanying the humanitarian aid flotilla headed to Gaza.

The Paris-based media advocacy group said the journalists should not be confused with activists and urged Israeli authorities to release them — along with their equipment.

The group said Wednesday it knew of 16 journalists held at Beersheba detention centre, including some from major Western dailies The Sydney Morning Herald and Frankfurter Allgemeine Zeitung.

On Tuesday, the United Nations Security Council issued a statement calling for a prompt and impartial inquiry into the raid. The statement also said the current situation in Gaza was "not sustainable."

Reports suggest pro-Palestinian activists plan on sending more ships to Gaza.

With files from The Associated Press