Asked about the possible involvement of Usama bin Ladin's group, Gul told reporters: "As a result of this investigation a trace has been found. Links have been uncovered."
Al-Qaida claimed responsibility for the blasts, a London-based Arab newspaper reported a day after. Investigations into the blast seem to corroborate the claim.
A total of 25 people were killed in the attacks on Saturday, when bombers drove explosives-laden trucks at two synagogues in Istanbul during Sabbath prayers.
"In order to say this with a 100% certainty, we also have to wait for the DNA tests and they will probably be finalised today," Gul said.
"We see that a link has emerged with that organisation in Afghanistan at least on the level of mentality and ideology," he added.
"We see that a link has emerged with that organisation in Afghanistan"
foreign minister, Turkey
Forensic scientists were conducting DNA tests on pieces of flesh found at the bomb sites and comparing these to blood samples from relatives of four suspects, named in media reports as local radical Islamists with links to foreign groups.
Several Turkish dailies named the bombers as Mesut Cabuk and Gokhan Elaltuntas, saying their trucks were provided by another two men, believed to have fled to Dubai about two weeks before the attacks.
The four men had received military training in camps in Pakistan and belonged to an underground Islamist group linked with al-Qaida, according to the Hurriyet newspaper.