Philippine police have increased surveillance activities in Davao, Mindanao, to prevent terrorists from infiltrating the city where President Rodrigo Duterte rose to power. 

Alexander Tagum, director of Davao City police office, said that troops are now confronting the militants, and are on alert to limit their movements. 

President Duterte has declared martial law across the southern Philippines, after fighting broke out between government forces and ISIL-linked extremists in the city of Marawi on Mindanao. Dozens of people have been killed in the ongoing crisis.

Mindanao, the second biggest island of the Philippines, has struggled with several terrorist groups in recent years, including the Maute group and Abu Sayyaf.