The military used helicopter gunships to repulse the latest attacks, in which about 20 people were also wounded.
Four people were killed when their bus was waylaid by guerrillas in Carmen, North Cotabato late Wednesday.
As many as 12 other civilians and three guerrillas were shot dead as the MILF launched attacks on the highway near Kulambugan town, also in North Cotabato, firing on a bus and military and police outposts, military reports said.
MILF commander Abdulrahman Macaapar said in a radio interview that his forces attacked Kulambugan and shot up a passenger bus — killing two people on the spot — after the vehicle allegedly failed to stop at a rebel checkpoint.
Initial reports said the rebels opened fire with their automatic weapons, killing bus driver Rey Mark Duhaylungsod and Emilia Vidal, a passenger.
Macaapar, also known as Commander Bravo, admitted his forces wounded a large number of passengers aboard the bus and were holding several hostages in Kulambugan, near Pagadian City.
He warned the military not to attack his positions to avoid harming the hostages.
Regional military commander Maj. Gen. Generoso Senga said among the four killed in the Carmen bus attack was barangay chairman Dionisio Villaver of Carmen town, his nephew Jimmy Villaver and their two security escorts, Dodoy Arangotte and Junie Melencio.
Officials said 15 people were wounded in the attack, including Villaver’s wife, Genoveva, and their son John.
The bus hit a landmine which knocked it on its side, after which the MILF rebels, led by a certain Jamalil, blasted the vehicle with their rocket-propelled grenades and rifle fire, Senga said.
"The attack on civilians is a clear work of the terrorist," Senga said.
MILF spokesman Eid Kabalu admitted they were behind the attacks, saying they targetted Villaver because he had supported a military offensive against the rebels.
"The MILF is not attacking the civilians, the forces on the ground know what they (are supposed to) do — that is, to hit the military and its supporters," Kabalu said.
The number of hostages taken in the Kulambugan attack could not be independently confirmed but sources said four policemen were held after their outpost was overrun by the rebels.
Traffic on the highway near Kulambugan town, where a bridge was allegedly blown up by the rebels, was halted due to the attacks.
"Our purpose in staging this series of attacks starting today is to cripple the country’s economy," rebel leader Macapaar said.
Kabalu, for his part, denied any hostages have been taken. "The MILF is involved here. We do not deny that," he said, saying it was part of ongoing battles that began when the military launched a major offensive in February. But he denied the rebels took any hostages and claimed they only blocked the highway "to prevent civilians from passing there and getting caught in the crossfire."
Officials said about 500 rebels participated in the attack and took as many as 300 residents hostage.
Col. Ernesto Boac said the rebels also overpowered the Kulambugan police outpost and took the policemen hostages early yesterday. – With reports from Lino de la Cruz