Southern Command chief Lt. Gen. Narciso Abaya said the new attack was launched late Thursday by suspected Moro Islamic Liberation Front (MILF) guerrillas in Buluan town in Maguindanao.
He said the bombing did not disrupt power supply, which had been virtually restored after 18 million people were left in the dark for several hours Wednesday night.
Abaya said a second bomb was planted on another transmission tower in Pikit, North Cotabato, but it was safely defused late Thursday.
The state-run National Power Corp. (Napocor) said it would take at least a week to fully restore the damaged transmission pylons in Abaga substation in Baloi town in Lanao del Norte.
Napocor Southern Mindanao spokeswoman Bambi Capulong said they have to tap alternative power sources to supply the 900-megawatt daily requirement of Mindanao following the destruction of the steel towers in Baloi.
Capulong explained the power supply in Mindanao remained critical as only 500 megawatts can be generated.
"If we add up our sources at the moment, only that much can be supplied," she said.
This means some areas in Mindanao will still experience occasional power outages until all the Napocor’s destroyed transmission grids in the island are fully restored.
Napocor said at least P2 million will be spent to repair each toppled tower. Officials also estimated the transmission tower toppled in Baloi would cost P5 million in revenue losses.
At least 17 power relay towers, mostly located in secluded areas, have been destroyed since Feb. 11, a day after government forces launched an offensive against the MILF stronghold in Pikit which left almost 200 Muslim rebels dead.
MILF spokesman Eid Kabalu denied the rebel group’s involvement in the bombing of power transmission pylons in Mindanao even after the rebels vowed to retaliatory attacks against government forces.
The military blamed the MILF for the previous attacks on power pylons in Mindanao.
Army officials believe the attack on power pylons are reprisals for the capture of government forces of their stronghold in Pikit.
"Who else can do that? They are the ones who have those kind of explosives," Abaya said.
Last Wednesday’s total blackout occurred while 60,000 troops were placed on high alert in Mindanao to ward off what the military said were possible attacks by MILF guerrillas.
The attacks came after MILF chairman Hashim Salamat supposedly issued a "total war" order last week against government forces.
Despite the "total war" order, the government said it will still proceed with peace negotiations with the separatist rebels after President Arroyo secured the commitments of Malaysia and Libya in supporting the government efforts.
Lawmakers led by Surigao del Sur Rep. Prospero Pichay, chairman of the House committee on defense, called on the MILF to stop harassing military targets in Pikit and nearby towns to pave the way for the safe return of evacuees.
Pichay, who led the members of the defense committee on an inspection tour in Pikit, also appealed to the rebels to stop destroying power transmission lines.
"Otherwise the MILF could be labeled as terrorists and (that) would not be good for the peace talks," the Mindanao legislator said.
For his part, Davao City Rep. Prospero Nograles agreed on the possibility that the MILF may soon earn the terror tag if they indeed bombed the transmission tower bombings.
He also urged the MILF to spare these facilities since ordinary civilians suffer most from the power outages.
Malacañang also condemned the bombings and said the civilians suffer most from the sabotage attempts.
"Whoever did these (attacks) were clearly not taking into consideration the welfare of the civilians because the ones who really suffer here are the larger number of ordinary people," Presidential Spokesman Ignacio Bunye said.
Bunye also said the Armed Forces and the Philippine National Police (PNP) have been ordered to deploy men and secure the remaining power transmission pylons against further attacks.
He said the security arrangements being implemented by the military and the police in securing the transmission lines in Luzon will also be used in Mindanao.
As lawmakers made a tour of Pikit last Thursday, they were greeted by reports of sporadic clashes between government forces and the MILF.
There were also several cases of military detachments being fired on by MILF rebels although there were no reports of casualties.
Army spokesman Maj. Julieto Ando said troopers from the 7th Infantry Battalion and MILF guerrillas clashed in Barangay Lagandang in Isulan, Sultan Kudarat, three hours before the congressmen led by Pichay held an hour-long dialogue with military officials.
Ando said the skirmishes in Barangay Lagandang immediately spilled over the same day to nearby Barangay Pamatian in Esperanza, Sultan Kudarat, where patrolling soldiers also figured in a firefight with a band of MILF rebels. – With reports from Edith Regalado, Paolo Romero, Marichu Villanueva, Jose Rodel Clapano, Mike Frialde, John Unson, AFP