MANILA, Philippines -- Government troops are on guard against "desperate" communist insurgents who continue to warn of more attacks even as their numbers dwindle, Defense Secretary Gilberto Teodoro Jr. said Monday.

Teodoro issued the statement after the New People's Army (NPA) said it would attack businesses, including mining firms, as the rebel force marked its 39th founding anniversary over the weekend.

"The more they weaken, the more desperate they become, and we have to guard against that. Desperation, you know, conjures up more violent and more vile forms of reactions sometimes, and we really have to guard against such eventualities," he said.

"We enjoin vigilance on the part of business establishments to be more security conscious and aware of their surroundings," he added.

Teodoro said the rebel threat "borders on terrorism" and should be "condemned to the highest degree."

"The general plan to guard specific communities is there and, perhaps, through adequate intelligence work, commanders in certain areas may want to factor into their preparations such a fact," the defense chief said, when asked how troops would thwart the rebels' plan.

At the end of 2007, the military estimated the strength of the NPA, the armed wing of the Communist Party of the Philippines, at 5,700.

President Gloria Macapagal-Arroyo has given security forces until the end of her term in 2010 to defeat the communist insurgency, destroy Islamic extremist groups, and contain the Muslim rebellion.