Turkey: New group behind latest Istanbul attacks
Police established the suspects "were about to carry out new suicide attacks after making plans and carrying out reconnaissance work," Guler said.
He added: "we know they received political and military training in camps in Afghanistan and Pakistan", but police had so far found no links between them and al-Qaida.
"It does not have links to currently-known organisations … We are investigating whether it has links with al-Qaida," Guler added.
Statement received
The London-based Arabic newspaper al-Quds al-Arabi said last week it had received a statement from an al-Qaida linked group, Jund al-Quds, or Soldiers of Jerusalem, claiming responsibility for the bombing.
The attack on the freemasons left two dead – including one of the bombers – and five injured.
It came nearly four months after four massive bombings in Istanbul which Turkish authorities blamed on Turks with links to al-Qaida.
Guler also said one of the suspects arrested had confessed to the 2003 killing of a Jewish dentist in Istanbul.