Heavy fighting has broken out in the southern Philippines between government troops and Muslim rebels. At least 21 people have been killed.
The Philippine army says a group of Muslim rebels from the Moro Islamic Liberation Front attacked two army detachments in Maguindanao Province, on the southern island of Mindanao, Sunday night.
The Army says 13 rebels and eight soldiers were killed in initial clashes. Government troops retaliated with mortar fire and helicopters fired rockets to drive back the guerillas. The fighting continued Monday.
Army spokesman Lieutenant Colonel Buenaventura Pascual says both sides suffered casualties, and the rebels were continuing to attack Monday afternoon.
"Right now, the first detachment, the Linantangan patrol base, is being overrun by the MILF," he reported.
The fighting threatens to undermine a ceasefire between the two sides. The chief government peace negotiator, Brigadier General Alexander Yano, is due to travel to the south and meet with his MILF counterpart Tuesday in an attempt to diffuse the situation.
An MILF spokesman says it is not clear which side violated the ceasefire, and the rebels want international peace monitors from Malaysia, Brunei and Libya, who are already in the South, to investigate the incident.
Officials say the attack may have been a retaliation for the killing of the brother of an MILF commander last week.
The MILF has been fighting for an independent Islamic homeland in the southern Philippines for more than three decades.
The organization has been engaged in peace talks with the government since 2001. But the military says renegade MILF commanders are meanwhile giving training to members of the regional terrorist network, Jemaah Islamiyah.