The New People’s Army (NPA) is "trying to mass forces" in certain areas, including Northern Luzon and some central islands, Brig. Gen. Eduardo Purificacion said over ABS-CBN.
"They take potshots at certain localities where they deem the military is weak," or "attack or harass certain detachments which are away from" populated areas, he added.
Other officials say the NPA has stepped up attacks on so-called "soft" targets such as telecommunications and power facilities.
Last week, Philippine National Police chief Director General Hermogenes Ebdane urged telecommunications firms to spend more to secure investments worth hundreds of millions of dollars from NPA attacks.
"The Armed Forces has redeployed more forces (to) priority threat areas," Purificacion said.
NPA membership has declined at least 23 percent to about 9,000 from between 12,000 and 13,000 two years ago, he said.
Of that number, at least 5,000 are considered "armed regulars" compared to about 6,000 in early 2001.
Government forces have rolled back the NPA in more than 400 of the 2,751 villages where they used to operate, Purificacion said.
"Slowly but surely, we are winning back the confidence of our people," he said.
Last week, National Security Adviser Roilo Golez said that heavy military and political setbacks were forcing the NPA and its mother organization, the Communist Party of the Philippines (CPP), back to the negotiating table.
President Arroyo suspended talks with the communists in mid-2001 after the rebels assassinated two legislators.
Last year, the United States included the NPA and the CPP in its international blacklist of "foreign terrorist organizations."
Washington, Canada and a number of European governments also agreed to track down and stop the rebels’ foreign funding sources as well as to freeze their overseas assets. – AFP