Israel's storming of the Turkish ship and killing of nine Turks a week ago has loomed over the Eurasian and Middle East security talks in Istanbul, which began on Monday and will move to a full summit on Tuesday.
"The time has come to lift the embargo on Gaza," Turkey's Prime Minister Tayyip Erdogan told a joint news conference with Syria's President Bashar al-Assad of Syria.
"We don't want an open air prison in the world any more," he said.
Once close allies, Israel and Turkey's relations have been on a downward spiral since Erdogan began championing the Palestinian cause after an Israeli offensive in Gaza in 2008.
The Turkish leader has said Israel would have to pay for killing Turks in the botched commando raid.
"Israel has to pay the bill for the blood that has been shed by the martyrs," said Erdogan, who has become a folk hero in the Middle East for his attacks on Israel.
The Syrian leader pledged to support Turkey in action and words in its campaign for an end to the blockade.
"I would like to say Turkish blood is not different from Arab blood," Assad said. "Our blood is one, and this combination will eliminate the blockade of Gaza."
Damascus would stand by "every decision" made by Turkey to see Israel lift its blockade of the Gaza Strip, Assad said, adding: "We are not just about condemnation, we are about actions."
Assad added his own criticism of the flotilla raid, calling it not "just another crime, but a crime that exposes Israel's true face."
"We came to Istanbul to condemn Israel's crime," said Assad. "We are not just people who talks and issue declarations of condemnation. We are in favor of actions, and we declare that we will support every decision and every step that Turkey requests in order to break the blockade, including support of an international inquiry."
"It is clear to the world that the peace activists arrived with a goal of peace," added Assad. "The whole world, including Israel, knew in advance that it was a Turkish boat, sailing under a Turkish flag. Israel always commits crime, but it has always accused those it killed of terrorism. This time, Israel cannot accuse its victims of terror."
Turkey also received messages from support from other Muslim countries, including Afghanistan, Azerbaijan, Iran, Pakistan, Qatar and, of course, Palestinian leader Mahmoud Abbas.
"Pakistan condemned in the strongest possible terms the unjustified aggression shown towards the freedom flotilla," Pakistan Foreign Minister Shah Mahmood Qureshi said. "We stand by you."
It is doubtful whether the final declaration by the Interaction and Confidence Building Measures in Asia forum (CICA) will contain a condemnation of Israel, as the wording has to be reached by consensus, and Israel is a member.
Though it decided against exposing any senior official to Turkey's fury at an international forum, Israel was represented by its consulate-general.
CICA includes a diverse group of 20 countries, but many other countries' leaders – such as Assad - have come as guests.
While not expecting much from CICA, Turkey is using the chance to gather diplomatic support against Israel.
On Wednesday, Arab League foreign ministers are due to meet in Istanbul for talks with their Turkish counterpart.
Israel has rejected a proposal by UN Secretary-General Ban Ki-moon for a multi-national investigation and said it had the right to launch its own inquiry. It has said its forces acted in self-defense after they were set upon by pro-Palestinian activists wielding clubs and knives.
Erdogan dismissed Israeli allegations that some of the aid workers on board the Mavi Marmara aid ship had militant links.
"They are like a lying machine. They are making up lies. That's what they are known for," the Turkish leader said.
The diplomatic offensive against Israel has overshadowed other business at the summit, being attended by eight visiting presidents, plus Russia's Prime Minister Vladimir Putin.
Iran's President Mahmoud Ahmadinejad, who has called for Israel to be "wiped off the map", met with Turkey's President Abdullah Gul on Monday.
According to a Turkish official, Gul urged the Iranian president to show the world that Tehran was ready to cooperate to remove fears concerning its nuclear program.
Ahmadinejad criticized Putin last month for backing moves to draft sanctions against Iran last month, and there are no plans for them to meet during the CICA summit.
Turkey, NATO's only Muslim member and a candidate to join the European Union, has sought to raise its international profile in recent years, mediating in issues ranging from Afghanistan/Pakistan ties to Iran's nuclear program.