ANKARA — Israel's allies froze military ties and summoned its ambassadors Monday over the storming of an aid flotilla bound for Gaza, as Muslim leaders slammed the deadly raid as "criminal" and "inhuman".

UN Secretary General Ban Ki-moon said he was "shocked" by the Israeli navy's assault on a convoy carrying hundreds of pro-Palestinian activists, lawmakers and journalists through international waters towards besieged Gaza.

Ban called on Israel to "urgently" explain itself over the raid, which Israel's Channel 10 TV left 19 passengers killed and 36 wounded, many of them Turks.

Israel's closest ally Washington described the loss of life as a "tragedy," on the eve of talks between President Barack Obama and Prime Minister Benjamin Netanyahu.

"The United States deeply regrets the loss of life and injuries sustained and is currently working to understand the circumstances surrounding this tragedy," a White House spokesman said.

As the Vatican voiced "deep sadness and concern" and Middle East peace envoy Tony Blair expressed "deep regret and shock" at the loss of life, capitals across Europe summoned Israel's ambassadors to explain the assault.

Ankara responded with fury, recalling its ambassador from Tel Aviv and warning the assault would have "irreparable consequences" to bilateral ties.

Police held back angry crowds shouting "Damn Israel" outside Israel's missions to the country, as Turkey accused Israel of a "flagrant breach of international law," and "disregard for human life and peaceful initiatives."

Deputy Prime Minister Bulent Arinc also said plans for three joint military exercises with Israel had been scrapped.

Greece, which had dozens of nationals in the convoy, pulled out of joint military exercises with Israel and cancelled a visit by its air force chief, as an aid group claimed that commandos in helicopters had fired on a Greek vessel.

Israel said its troops were attacked after they stormed six ships loaded with thousands of tonnes of aid and with hundreds of activists aboard, and that both sides used live fire.

Muslim leaders united in condemning what Palestinian president Mahmud Abbas called a "massacre" and Arab League chief Amr Mussa said was a "crime."

The Islamist movement Hamas which rules Gaza urged world Muslims to "rise up" in protest, as Iran's President Mahmoud Ahmadinejad denounced the raid as "inhuman Zionist regime action."

Lebanese Prime Minister Saad Hariri called for an emergency meeting of the UN Security Council, which his country currently chairs.

Pakistan's Prime Minister Yousuf Raza Gilani "strongly condemned" the attack on a "peaceful flotilla," as politicians, lawmakers and journalists staged a peaceful protest in Islamabad against Israel.

Egypt condemned the "acts of killing" by Israel forces while Kuwait's parliament speaker said the storming of the flotilla, which was carrying 16 Kuwaitis including an MP, was a "heinous Israeli crime."

And Indonesia, the world's most populous Muslim nation, said "there was no basis" for Israel's assault.

In Europe, condemnation was equally swift.

The European Union foreign affairs chief Catherine Ashton demanded Israel mount a "full inquiry," as member states ordered an emergency meeting of their ambassadors to the EU.

Spain -- the current European Union president -- France, Sweden, Norway, Denmark, Austria and Greece summoned Israel's respective ambassadors, with Madrid slamming the operation as "unacceptable".

France's President Nicolas Sarkozy accused Israel of a "disproportionate use of force."

Germany's Foreign Minister Guido Westerwelle said he was "deeply concerned" about the deaths, while Italy's Foreign Minister Franco Frattini "deplored" the loss of civilian life.

British Foreign Secretary William Hague similarly deplored the loss of life, saying Israel must "act with restraint" -- but also said London had warned of the risks of attempting to access Gaza in defiance of the blockade.

Thousands of Palestinian refugees and activists demonstrated across Lebanon to denounce the raid, some chanting slogans like "Give us weapons, give us weapons and send us on to Gaza."

Maen Bashur, a Lebanese coordinator for the mission, said activists considered those seized on board the ship as "war prisoners".

A Cyprus MEP Kyriacos Triantafyllides, who was involved with the mission, said activists had "expected a strong reaction from Israel."

"But nobody believed it would come to this point, where they would face something akin to an invading army," he said.