But National Security Adviser Norberto Gonzales played down the likelihood that the suspects had acquired the ability to use chemical weapons when they were arrested in March.
Among the items captured from the six suspects were "readings on biological and chemical warfare," Gonzales told Agence France Presse.
He said the documents seized were more of the "anarchist handbook" type readily available from certain publishers, rather than confidential military documents.
"It doesn’t mean they have the capability (for chemical weapons) and are already manufacturing them," he said.
The significance of the find is that "it gives us a look into the mental framework of terrorists. What they really want is as many casualties as possible," Gonzales said.
Seized from the six suspects were more than 50 kilos of trinitrotoluene (TNT) and other bomb components for their planned "Madrid-level" bombing attacks in Manila, Gonzales said, referring to the March 11 bombing of commuter trains in the Spanish capital that claimed nearly 200 lives.
The suspects led by Alhamsar Manatad Limbong, alias Hassan Sayyaf Kosovo, were arrested on March 29 in their hideout in Fairview, Quezon City. They were positively identified by their former kidnap victims as among those who held them hostage along with foreign nationals in the spate of kidnap-for-ransom incidents in Basilan and Sulu in 2000 and 2001.
Gonzales denied speculation that the Abu Sayyaf or similar regional terror groups, like the Jemaah Islamiyah (JI), might have established a chemical or biological weapons facility in the southern Philippines.
The Abu Sayyaf, which for years have sporadically terrorized Mindanao and Metro Manila, publicly admitted its links with the Afghanistan-based al-Qaeda of the elusive terrorist Osama bin Laden and the Jakarta-based Jemaah Islamiyah. — AFP, John Unson