The gunmen have mustered a force of about 200 and fought a series of skirmishes with the security forces this year after government forces retook Marawi last October, Colonel Romeo Brawner told AFP.
Al Qaeda urges people to topple government as Egypt prepares for polls
"They have not abandoned their objective to create a caliphate in Southeast Asia," said Brawner, a senior commander for a military task force that has since been protecting Marawi.
"Mindanao is the most fertile ground," he said, referring to the Philippine's southern region. "Our countrymen are more vulnerable (to recruitment)."
Struggling with widespread poverty and armed Muslim insurgencies seeking independence or self-rule, Mindanao must improve poor supervision of Islamic schools or madrasas where most young gunmen are recruited, he added.
He said the armed forces were retooling to meet the challenge of the Maute group, which occupied Marawi over five months and has pledged allegiance to Islamic State group.
Gunmen who escaped during the early days of the US-backed operation to recapture Marawi are leading the recruitment effort, flush with cash, guns and jewellery looted from the city's banks and private homes, Brawner said.
The recruits are mostly locals, but an unspecified number of Indonesians, some with bomb-making skills, have recently arrived there, he said.
Mindanao military officials said Maute gunmen murdered three traders in the town of Piagapo, near Marawi, in November.
The military killed three militants in Pantar, another neighbouring town, on February 8, while police last month arrested three suspects over the Piagapo merchant killings.
The military also reported skirmishes with Maute gunmen in the towns of Masiu and Pagayawan near Marawi last month.
The renewed fighting came after Philippine President Rodrigo Duterte and other political leaders in the Mindanao region warned of a potential repeat of the siege of Marawi which claimed more than 1,100 lives.
Duterte has imposed martial law over Mindanao until the end of the year in an effort to curb the militants' activities.
Ebrahim Murad, head of the Philippines' main Muslim rebel group the Moro Islamic Liberation Front, which signed a peace treaty with Manila in 2014, also warned Tuesday that militants were recruiting and could seize another city.
Murad said the 10,000-member MILF was battling pro-IS groups for influence in schools as the militants worked to infiltrate madrasas and secular universities.
At the same time IS gunmen were making their way into the southern Philippines from Malaysia and Indonesia, he added, but gave no estimates.
Islamic State stronghold in Afghanistan is a threat to regional peace, says Ahsan Iqbal
Speaking separately to reporters Friday, Brawner said the rebuilt Maute forces currently "do not as yet have the capability to launch another attack like what they did in Marawi", though he added this could change.
The siege of Marawi forced the Philippine military, more used to low-intensity jungle warfare against guerrillas, to reorganise and to rewrite their doctrines, with a new emphasis on urban warfare training, he said.
"So (on) the side of the armed forces we are ready for another Marawi siege, whether it happens in Marawi or elsewhere," Brawner said.
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ