MANILA, Philippines — Thousands of protesters marked Thursday’s anniversary of the 1972 declaration of martial law by late Philippine dictator Ferdinand Marcos with an outcry against what they say are the current president’s authoritarian tendencies and his bloody crackdown on illegal drugs.

Hundreds of riot police were deployed to secure the marches and rallies, among the largest against President Rodrigo Duterte since he took power last year, although a new survey by the Washington-based Pew Research Center showed the president and his anti-drug campaign are widely popular in the Philippines.

Pro-Duterte followers also staged rallies in Manila. The rival demonstrations reflected deepening divisions sparked largely by the president’s brutal anti-crime style.

Duterte warned he will use force or expand nationwide his declaration of martial law in the country’s south if the anti-government protesters threatened public order.

In May, he placed the southern third of the largely Roman Catholic nation under martial law to deal with a siege by pro-Islamic State militants in southern Marawi city that has dragged on for nearly four months.