MANILA - President Rodrigo Duterte on Friday admitted “underestimating” the reported build-up of extremist forces in Marawi City, which eventually led to its siege in May 2017.

Duterte said he is taking full responsibility for it.

“We are aware of the build-up, but we underestimated. As commander-in-chief of the AFP and the police, there is nobody to blame, but me,” he said in a speech at a forum in Lapu-Lapu City, Cebu.

The five-month Marawi siege began when the Maute group, led by brothers Omar and Abdullah, captured parts of the city in an alleged bid to establish an Islamic State province in Mindanao.

The clashes erupted after government troops attempted to arrest Abu Sayyaf senior leader Isnilon Hapilon in the city on May 23.

The conflict prompted Duterte to put the entire Mindanao under martial law.

At least 1,100 people, mostly terrorists, were killed in the 5-month siege.