Military explosives were used in a huge bomb blast at a Manila shopping mall that left nine dead and 113 injured, Philippine police said on Saturday.
Evidence collected from the Glorietta mall blast site indicates that the bomb "contained RDX, the main chemical component of C4," the police said in a report to President Gloria Arroyo.
In the Philippines C4 explosive is only used by the military.
The report was delivered at a top-level security meeting between the President and her security advisers at police headquarters in Manila.
It said that investigators' initial findings showed the bomb used in the deadly blast contained chemicals normally used in C4.
Arroyo immediately ordered the Country's police chief General Avelino Razon to check its source and pinpoint the culprits.
"Is that already definitive, or are there other detailed findings?" Arroyo said during the briefing. "We need regular information bulletins on the status of this information."
Razon said investigators were continuing to sift through the rubble for more clues, and that rescuers pulled out one more body from the blast site early Saturday. The toll now stands at nine dead and about 100 injured, an updated medical bulletin said.
No group has claimed responsibility for the blast, which came weeks after military intelligence, foiled an alleged plot by Al Qaeda-linked Abu Sayyaf Islamic militants to bomb the southern port city of Zamboanga.
Reports said officials from the US Federal Bureau of Investigation (FBI) were helping Philippine police in the probe.
Throughout the night bomb experts sifted through blast debris trying to find clues as to what sort of bomb was used.
"The investigation is continuing," Razon said.
The mall remained sealed on Saturday, with a cordon of policemen guarding its perimeter.
Razon said the bomb was apparently left at a delivery bay near a popular Chinese restaurant at the mall shortly after lunch.
He said investigators were also reviewing closed circuit television cameras and interviewing survivors and witnesses.
Alfie Reyes, a spokesman for the mall owners Ayala Land, said the firm would pay all medical expenses for the victims.
"This is very saddening. Those who perpetrated this committed a very cowardly act to hurt civilians. It is an act we deplore, we condemn it in the strongest possible manner," he said.
He said about 100 retail shops would be affected, but structural engineers have said that other sections of the mall could be re-opened.
Officials and witnesses said the explosion left an eight-metre (26-foot) wide crater on the ground floor and blew a hole through the roof on the second floor.
Islamic militants were blamed for the bombing of a bus near the Glorietta mall that killed four people on Valentine's Day in February 2005.
Militants also firebombed a ferry in Manila Bay the previous year, killing more than 100 people in the country's worst terrorist attack.