IS-linked militants strengthening in southern Philippines
Around 200 jihadi fighters have fought a series of skirmishes with the security forces in the first two months of the year, Colonel Romeo Brawner told AFP.
"They have not abandoned their objective to create a caliphate in south-east 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 Philippines' southern region. "Our countrymen are more vulnerable (to recruitment)."
IS-linked insurgents have thrived in parts of the Muslim-majority south, which has suffered from poverty and a lack of infrastructure.
Many of the militants have been recruited from Mindanao's Islamic schools or madrasas, and supervision of them must improve, Brawner said.
Philippines troops are now gearing up for more battles with the IS-linked Maute group, which occupied Marawi city before its fall to the government in October.
Some militants managed to escape Marawi before the US-backed offensive began.
They are now leading recruitment efforts, obtaining funds and tooling up for new battles with government forces.
In addition to local recruits are a number of Indonesians - some with bomb-making skills.
Three traders were murdered by Maute militants in the town of Piagapo, near Marawi, in November, the military said with three suspects arrested last month.
Three jihadi fighters were also killed by the military in Pantar, another neighbouring town, early February.
Skirmishes between the military and Maute gunmen have also broken out 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.
Martial law has been established 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 [MILF] - which signed a peace treaty with Manila in 2014 - warned this week that the IS-linked militants could seize another city in the Philippines' south.
Murad said the 10,000-member MILF was battling pro-IS groups for influence in schools as the jihadists worked to infiltrate madrasas and secular universities.
IS-inspired recruits were making their way into the southern Philippines from Malaysia and Indonesia, he added, but gave no estimates.
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.
Philippines troops were introduced to a new form of warfare with the siege of Marawi, after spending years involved in battles in the jungles of the south.
"So (on) the side of the armed forces we are ready for another Marawi siege, whether it happens in Marawi or elsewhere," Brawner said.