Malacanang urged on Sunday Filipinos to cooperate against "faceless enemy" as the world commemorated the 9/11 terror attacks in the United States.

In an interview over state-run dzRB Radyo ng Bayan, Presidential Communications Office Secretary Martin Andanar said the September 11, 2001 attacks on the US opened a "Pandora's box" in terrorism.

"As a matter of fact, this developed also into something really even worse. There came the extremists, the ISIS (Islamic State of Iraq and Syria)," he said, adding that even the local terrorist Abu Sayyaf Group has become "stronger."

"This is a reminder that all of us are facing a faceless enemy, the terrorists. And we should all be one in battling this, we should all be helping each other," he said.

Andanar said the fight against terrorists should not be left only to the Philippine National Police and the Armed Forces of the Philippines.

"This is a responsibility of every Filipino," he said.

Nearly 3,000 people were killed and thousands were injured when the al-Qaeda terrorists crashed four passenger aircraft into the World Trade Center in New York City, Pentagon, and in Pennsylvania 15 years ago.

Andanar noted that there were Filipinos who were also killed in the attacks.

On September 2, a bomb exploded in a night market in Davao City, killing 14 people and injuring 70 others. The explosion was allegedly perpetrated by the Abu Sayyaf bandits. DMS