MANILA, July 7 (Xinhua) -- Two separate blasts rocked the restive southern Philippines and killed six civilians Tuesday morning, bringing the death toll to 12 in bombings there over the past three days, officials said.

    Around 7:50 a.m. local time (2350 GMT Monday), an improvised bomb -- attached to a motorcycle -- went off in front of a store, about 100 meters from a Mt. Carmel church in Jolo, Sulu province, killing two civilians and wounded about 40 others, including three policemen responding to the information from civilians who noticed protruding electrical wires on the parked motorcycle. Many of the injured were in critical condition and soon the fatalities went up to six.

    After the blast, two more unexploded improvised explosive devices were recovered by bomb experts, which were sealed inside a cardboard box a few meters away from the church in Jolo proper.

    Only three hours later, another bomb, rigged in a 1987 model Mitsubishi Lancer car, exploded in the southern Iligan City, injuring 13 people, including three government soldiers.

    The twin blasts occurred two day after another one that claimed six lives and wounded about 55 others in the southern city of Cotabato.

    Lt. Col. Arnulfo Marcelo Burgos, spokesman for the Philippine Army, tagged rogue members of the separatist Moro Islamic Liberation Front (MILF) as behind the incidents in Iligan and Cotabato.

    The MILF is the largest rebel group in the Philippines with more than 11,000 members, which has been fighting decades to establish an independent Islamic state in the southern region of Mindanao. Earlier, government officials said they expected to resume peace talks with the Muslim rebels later in the month. It's not clear whether the plan will be affected by the bombing attacks.

    Burgos said the military believe that the bomb used in the Iligan blast was the handiwork of the rogue rebels. The bomb was composed of an 81-mm mortar round and similar to the one used in the bombing in front of the Cotabato City cathedral on Sunday, which was also blamed on the rogue rebels, according to the official.

    Director General Jesus Verzosa, chief of the Philippine National Police on Tuesday placed all police offices in Mindanao under full alert condition in the aftermath of the series of bomb-related incidents.

    Verzosa instructed police units in the affected areas to coordinate closely with the local crisis management committees for an organized response to the incidents, including post-blast investigation and identification of suspects responsible for the attacks.

    "Our immediate concern is to extend assistance to casualties hurt in the incidents, and to prevent the situation from getting out of hand," said Verzosa.

    "Post-blast investigation will continue after we have rendered the crime scene safe for our technicians. The investigation will gather evidence and seek to determine any peculiar signature in the improvised explosive devices, and to determine if the three incidents in Cotabato, Jolo and Iligan were coordinated," he added.

    Meanwhile, the police chief urged the public to remain calm despite these emergencies, and to be vigilant against any threat to public safety and security.