MANILA, Philippines--The Philippine National Police still has to identify individuals or groups suspected of staging recent bomb-related incidents in three Quezon City locations, a week since the attacks spurred talk a purported plot to sow fear among the public.

PNP spokesperson Senior Supt. Leonardo Espina said investigators from the Quezon City Police District were carrying out a careful scientific investigation before publicizing names of suspects, even while the military tagged two unnamed groups in the attacks.

“The QCPD is still winding up its investigation. We were informed that they're still into it, they haven't concluded the investigation, because this is crucial prior to naming whoever suspects,” Espina said.

“If the question is, are there suspects? There is none as of now. We have to operate very scientifically before we can pinpoint any suspects,” he added.

The military said Thursday that two groups were being looked at as possible plotters of last Sunday's blast at the Office of the Ombudsman and the discovery of improvised explosive devices at the Department of Agriculture and the vicinity of the One Burgundy Plaza, a condominium building on Katipunan Avenue.

Bombs recovered in the latter two locations were said to be made of military-grade C-4 explosive.

“The investigation is now at the stage of analysis of the bombs, because we can see telltale signs, from where you can derive probably the motive behind, the identity of the most probable suspects,” Espina said.

Asked whether the military statement preempted police investigation, he said: “Not really.... On the part of the PNP, we are moving scientifically. Let's see the conclusion first on the bomb signature before we can say who were behind them.”

While on normal alert nationwide, the PNP stepped up security around government buildings and public areas in Quezon City following the string of bomb-related incidents.

The National Capital Region Police Office has also started preparing its security plan for President Macapagal Arroyo's State of the Nation Address on July 27, when protest actions are expected to be held outside the Batasan complex.