Updated

Thousands of protesters are marking the anniversary of the 1972 martial law declaration by the Philippines then-dictator Ferdinand Marcos by raising an outcry against what they say is the current president's authoritarian tendencies and his brutal anti-drug crackdown that has shocked Western governments.

Hundreds of riot policemen were deployed Thursday to secure the marches and rallies, which are expected to be among the largest against President Rodrigo Duterte since he took office last year.

He has warned he would use force or expand his martial law declaration in the south nationwide if the protesters threaten public order.

Pro-Duterte followers are also staging rallies, and police say they would guard against possible confrontations.

Marcos' martial law era had been marked by massive human rights violations and muzzling of civil liberties.