Evidence is growing that Saturday's twin attacks on synagogues in Istanbul were carried out by suicide bombers.
The blast left a crater outside the Neve Shalom synagogue
At least 23 people are now known to have died in the attacks, and more than 300 others were injured.
Turkish and Israeli experts are working at the scene, which was visited earlier today by Israel's foreign minister.
Meanwhile Turkish Prime Minister Recep Tayyip Erdogan stressed that he would stop at nothing to bring those responsible to justice.
"Our determination to fight terrorism in the international arena continues because this event has international links," he said.
Jewish communities in Europe have expressed alarm at what they fear is a new anti-Semitic campaign by Islamic radicals.
The European Jewish Congress said it would hold urgent consultations on Monday with Italian Prime Minister Silvio Berlusconi, who holds the rotating presidency of the European Union, to voice its concern.
Israeli security agents and Turkish police picked through debris in a search for clues.
The bombs, which went off minutes apart on Saturday morning, badly damaged both buildings and scattered wreckage over a wide area.
According to Turkish media reports, the attacks were caused by suicide bombers driving two trucks, each loaded with 400 kilograms of explosives.
Two of the corpses were found to have wires attached to them suggesting that they might be bombers, the reports said.
Interior Minister Abdulkadir Aksu told Associated Press that the chances of the attacks being carried out by suicide bombers was "more than 95%".
"I am not saying 100% because the investigation is still under way, but I was convinced that these attacks were suicide bombings after I saw the scenes of the attacks and was briefed by the authorities," he said.
The BBC's Richard Galpin in Istanbul says Turkey has been quick to point the finger at international radical groups and has not ruled out the possibility that al-Qaeda was involved.
The level of sophistication required to carry out the attacks was beyond any local organisation, our correspondent says.
Turkish officials are therefore treating with scepticism a claim by a Turkish Islamist group, the Great Eastern Islamic Raiders' Front, that it carried out the attack.
Israeli Foreign Minister Silvan Shalom visited the bombed synagogues in the districts of Beyoglu and Sisli, accompanied by the mayor of Istanbul and the city's chief rabbi.
He laid wreaths at the sites as Turks threw down white carnations in a sign of condolence.
Our correspondent says his visit was clearly intended to signal that Israel and Turkey would co-operate closely in the aftermath of the bombings.
Most of those killed in the attacks were Muslim Turks, who lived, worked or were passing by the synagogues when the explosions occurred.
Six Jews were also among the dead and accounted for about half of those injured.
The Italian embassy said an Italian citizen, 57-year-old Romano Jona, was killed in one of the blasts, AP reported.
Turkish and world leaders have condemned the attacks, which happened as the synagogues were holding Sabbath morning prayer services.