Cotabato City, Philippines - Fire razed a Philippine military ammunition depot in the troubled southern region of Mindanao on Friday, triggering a series of explosions that caused panic among nearby residents.

Major Randolph Cabangbang, a regional military spokesman, said the cause of the fire was still being determined, but assured the public that sabotage was not involved in the incident.

He said the depot inside Camp Siongco in Datu Odin Sinsuat town in Shariff Kabunsuan town, 930 kilometres south of Manila, was completely destroyed by the fire.

"No need to be alarmed," he said. "Nobody was hurt, and the ammunition stored in the warehouse are old, defective and were scheduled for disposal."

"An investigation is ongoing to determine the cause of the fire and in order to prevent a similar occurrence in the future," he added. "Definitely, it was not sabotage."

Cabangbang noted that since most of the ammunition in the depot were old, they could easily spark and explode.

Lieutenant Colonel Julieto Ando, an army division spokesman, said nearby residents panicked and called for military assistance when the fire caused 30 minutes of explosions of 60-millimetre and 81-millimetre mortars before dawn.

He said the fire was contained after two hours.

"We are on red alert," he added.

The fire occurred as troops continued to hunt down rogue commanders of the separatist Moro Islamic Liberation Front, who led a series of deadly attacks in August following a setback in peace talks with the government. (dpa)