JAKARTA, Indonesia — The central command of the Islamic State in Syria has funneled tens of thousands of dollars to militants in the Philippines over the last year, most likely aiding their spectacular seizure of the southern Philippine city of Marawi, a report released Friday said.

The report from the Institute for Policy Analysis of Conflict, a research institute based in Jakarta, describes how Mahmud Ahmad, a high-level Islamic State figure from Malaysia, who is based near Marawi, worked through the group’s chain of command to Syria to get money and international recruits to help local militants seize territory in the Philippines for the caliphate.

The report provides insight into a question that has bewildered policy makers since militants affiliated with the Islamic State swept into Marawi two months ago: How were they able to seize an important city in the southern Philippines, and what if any role did the Islamic State’s central command play in the seizure?

The city has remained largely under the control of the militants for nearly two months despite a government military campaign to retake it with ground forces and aerial bombardments.