MANILA, Jan. 17 -- The Armed Forces of the Philippines (AFP) said Friday that it made significant gains in the domestic peace and security operations against insurgent groups in 2013, but admitted that they still poses a "potent challenge" to the country.

AFP chief of staff General Emmanuel Bautista said at military headquarters Camp Aguinaldo that in the case of the New People's Army (NPA), the leftist group "miserably failed" in achieving its goals bound on its Five-Year Central Plan which ended last year.

"They were unsuccessful in expanding their mass base support as 16 more provinces were normalized last year," he said.

With this development, Bautista said as of last year, 43 provinces out of the 64-NPA-affected provinces nationwide have been freed from the leftist insurgents.

He also cited that a total of 824 NPA combatants were neutralized and 425 firearms were gained in 2013. The neutralization used by the Philippine military means that those insurgents were either arrest, killed in military operations or surrendered.

In the case of the Bangsamoro Islamic Freedom Fighters (BIFF), a breakaway group of the Moro Islamic Liberation Front (MILF), the military chief said the AFP was able to effectively limit their capability to sabotage or derail the ongoing peace process between the Philippine government and the MILF.

The military is confronting other threat groups, including the terrorist group Abu Sayyaf and the rogue Moro National Liberation Front (MNLF) fighters under former MNLF chairman Nur Misuari.

Asked which among the threat groups poses the most challenge, AFP spokesman Major Domingo Tutaan said: "Well course the NPA is still the most potent challenge, it's a challenge to security, internal security and peace efforts that we have."

The Philippine military placed the rebel strength at "a little over 4,000" by the end 2012. Tutaan said it was possible that the insurgents were able to recruit new fighters last year, so the military can not release the current strength of the rebel group to avoid mistake.