A bomb has exploded near a shopping mall in the southern Philippines, a day after two bombs killed a dozen people in the region. Authorities say separatist rebels with links to a regional terrorist organization may be responsible for the attacks.

There were no report casualties after a bomb exploded in the southern Philippine town of Cotabato, around 1,000 kilometers south of the capital, Manila.

It was the third attack in two days. On Tuesday two bombs in the same region claimed a dozen lives and injured around 30 people.

Philippines officials say rogue elements of the separatist Moro Islamic Liberation Front, which is in peace talks with the government, may be responsible for the attacks.

Moro Islamic Liberation Front spokesman Eid Kabalu denies his organization is behind the bombings.

He says Philippine president Gloria Arroyo has asked for the joint government and Moro Islamic Liberation Front panel overseeing their ceasefire to investigate who is behind the attacks, and he says his group welcomes the move.

The Moro Islamic Liberation Front is the largest Muslim separatist group in the mostly Roman Catholic country. It is negotiating with the government to end more than three decades of fighting. But talks have stalled over the rebels' demand for a Muslim ancestral homeland in Mindanao.

The police and military say a rogue faction of the Moro Islamic Liberation Front is collaborating with another rebel organization, the Abu Sayyaf group.

The Abu Sayyaf, the smallest and most violent of the rebel groups in the southern Philippines, is linked to the regional terrorist network, Jemaah Islamiyah, and is suspected of sheltering dozens of its members.

The governor of North Cotabato, Emmanuel Pinol, says the bombings are not random acts of violence.

"We all understand that this is related to something bigger. It could be related to the stalled peace talks with the Moro Islamic Liberation Front," he said. "It could be related to the ongoing operations against the Jemaah Islamiyah."

Since August, about 6,000 Philippine troops have been carrying out an offensive in the southern island of Jolo, an Abu Sayyaf stronghold, trying to hunt down two of Jemaah Islamiyah's most wanted members, Indonesians named Dulmatin and Umar Patek.

Both men are key suspects in the 2002 bombing that killed 202 people on Indonesia's Bali Island.

Dulmatin's wife was captured and arrested last week in Jolo and security officials also took custody of the couple's two children.