"Let us hope there are no others," he continued, "but if there are, authorities are pursuing them, and I am sure they will be caught."
Claims of responsibility for the four bombings have come from several groups or individuals claiming to be affiliated with Osama bin Laden's al-Qaeda network.
Thursday's attacks hit the British Consulate and offices of the London-based HSBC bank, killing 30. Five days before, suicide bombers attacked two synagogues, killing 25. The four assailants also died.
At least one of Thursday's bombers is believed to be from Bingol, a Kurdish city in southeastern Turkey that was home to the first pair of suicide attackers.
Istanbul antiterror police said yesterday that they had arrested more than 10 people over the last two days in connection with the blasts.
"We have made important strides in the investigation," Turkey's Justice Minister, Cemil Cicek, told CNN-Turk television without elaborating.
The Turkish daily newspaper Milliyet reported that the Isuzu pickup trucks used to deliver the bombs to the British Consulate and Neve Shalom synagogue were both bought by a Turkish man on the same day from an Istanbul car dealership.
President Bush said Friday that the attacks showed that Turkey was a new front in the "war on terror."
But many Turks say he shares blame for the attacks because of his policies on Israel and Iraq. Demonstrators who turned out across Turkey's major cities yesterday morning hammered home that message.
"Bush has announced a crusade, saying, 'You are on our side, or you are on the side of terrorism,' " one protester told thousands of others at a peaceful demonstration in Istanbul's main Taksim Square.
"We are against both," the protester said. "We will not be the slave of Bush or terror."
Some demonstrators carried red carnations, a mourning color used in connection with terror victims. Hundreds of armed Istanbul police officers in riot gear kept a watchful eye.
Draped in a red and white Turkish flag and wiping away tears, Cimen Filiz Pasa said she hoped the public display of anger and grief would "stop these crazy happenings."
Contact reporter Soraya Sarhaddi Nelson at firstname.lastname@example.org.