Authorities in the Philippines say they have stepped up security measures for a huge religious procession taking place in Manila on Monday after receiving information suggesting it may be the target of a terrorist attack.

"We have serious threats from trustworthy and credible information sources that the Feast of the Black Nazarene will be attacked," Cesar Garcia, a presidential national security adviser, said Monday. "We are told that almost nine suspected terrorists from Mindanao, southern Philippines, are already in the capital and can carry out the attack."

The Feast of the Black Nazarene is an annual Catholic festival in the Philippines during which millions of devotees join a procession centered around a wooden statue of Jesus Christ.

President Benigno Aquino said Sunday that he had ordered law enforcement agencies, including the military, to ramp up security efforts around the procession, according to the official Philippines News Agency (PNA).

"I call on our fellow citizens to exercise the maximum vigilance and discipline leading up to, and during, the procession," the news agency cited Aquino as saying.

Mindanao is a predominantly Muslim autonomous region, which was set up in the 1990s to quell armed uprisings by people seeking an independent Muslim homeland in the Philippines, a predominantly Christian country.