The Philippine military has launched a full offensive against Islamic militants in the south, President Gloria Arroyo has announced.
The Philippine army has been burying its dead
Ms Arroyo said the assault, on Jolo island in Sulu province, was directed against "terrorist cells".
The army headquarters was temporarily moved to the south at the weekend to boost efforts to target the militants.
The move follows clashes between troops and militants in Jolo last week, that left 50 dead, including 25 soldiers.
The Moro National Liberation Front (MNLF) - which signed a peace deal with the government in 1996 - claimed responsibility for last Thursday's ambush, saying it was in retaliation for earlier army offensives.
But military officials have also blamed Abu Sayyaf, the smallest and most radical of the southern militant groups, which is accused of being behind some of the country's worst atrocities.
"As I speak, government forces are in full offensives against terrorist cells in Sulu," Ms Arroyo told a meeting of business leaders in Manila.
She did not spell out what terrorist cells she was referring to, but analysts say the term is normally used to describe Abu Sayyaf, which is accused by the US of having links to al-Qaeda and the regional militant group Jemaah Islamiah.
Ms Arroyo also made it clear that she had ordered the military not to do anything that threatened peace agreements already in place.
The government and the MNLF are due to meet for peace talks in Indonesia later this month.
Another militant group engaged in peace efforts with the government, the Moro Islamic Liberation Front (MILF), admitted involvement in clashes on Basilan island last month, in which 14 marines were killed, 10 of whom were beheaded.
The MILF accused the military of breaking the truce by moving into its territory, but denied being behind the beheadings.
An extra 1,000 soldiers have been deployed to Jolo to join the 4,000 troops already stationed there following last week's fighting.
In an unprecedented step, Ms Arroyo said the army headquarters would temporarily move to the city of Zamboanga on Mindanao island, close to the flashpoint islands of Jolo and Basilan, to boost the offensive.
Government troops, backed by US military trainers, have been hunting militants in the region's mountainous terrain for months, but last week saw some of the worst fighting so far.
Thousands of civilians in Jolo have since fled their homes, and officials have appealed for food, water and medicines as people gather in community centres and schools.