COTABATO Five Muslim civilians were killed and five wounded in an ambush by members of an armed Christian militia group, officials said Monday.

The victims were aboard a vehicle and returning home from a picnic in the Lanao del Norte when they were attacked on Sunday afternoon, regional brigade commander Colonel Benito de Leon told reporters Monday.

De Leon said no motive had been established for the attack, although local Muslim groups and leaders of the separatist Moro Islamic Liberation Front (MILF) said they suspect the Ilaga Christian militia.

'Based on the information from our men on the ground five were killed. We suspect the perpetrators to be Ilaga,' said MILF spokesman Mohagher Iqbal.

Numbering in the several hundreds, the Ilaga has recently resurfaced after nearly 20 years of relative inactivity. The Ilaga in September warned it would attack MILF positions and their sympathisers in retaliation for August raids in mostly Christian towns and villages that left more than 60 civilians dead and over half a million people displaced.

Iqbal did not say whether they planned to retaliate, but said the MILF was conducting its own investigation into the incident.