The bombs, rigged in order not to explode, were apparently designed to sow fear and panic.
NBI Director Reynaldo Wycoco said agents have identified the number of the cellular phone used by a certain "RSD Adrev" who claimed to be the spokesman for the group in several radio interviews.
"We have identified the cell phone number he used. We are now verifying it," Wycoco said. "It will not take us long before we finally identify him. It appears that the name he used was based on the acronym of a federalist group."
On March 26, police and military agents conducted a dawn raid in Payatas, Quezon City and arrested a possible suspect in the series of bomb scares.
But the suspect, believed to be a former member of the Moro National Liberation Front (MNLF), was charged only with illegal possession of firearms.
The suspect’s looks apparently did not match any of the three composite sketches which the authorities gathered from witnesses and security video footage from one of the places where the bombs were planted.
On March 27, the authorities also arrested three men in Taguig City on suspicion that they were involved in the bomb scares but were also subsequently released for lack of evidence.
The first two bombs were found and defused by police on March 18 in Makati City followed by the discovery of six other bombs in other places in Metro Manila.
Five other bombs, made of similar components, were also found at a shopping mall in General Santos City and a busy thoroughfare in Cotabato City.
The bombs, which were apparently rigged to scare people and not to explode, were accompanied by a "manifesto" demanding the creation of three federal states for the "tri-people of the Philippines."
The three federal states were named the "Tribal Federal State" for indigenous peoples nationwide, "Federal Islamic State" for Muslims and the "Federal Christian State" for Christians.
The authorities have dismissed the IPFSA as a "crackpot" group or possibly a front for four other genuine threat groups, identified as the MNLF, Moro Islamic Liberation Front (MILF), People’s Patriotic Movement (PPM) and the Rebolusyonaryong Alyansang Makabansa (RAM).
The RAM, however, has denied involvement in the bomb scares.
In several radio interviews, "Adrev" said they were not trying to scare people and the bombs they planted in Metro Manila last week were "warnings."
Adrev said his group, which allegedly includes members of 110 tribal groups, planted the bombs on its own and denied they had links with the MNLF or MILF.