Protests against US President Donald Trump erupted in the Philippine capital on Sunday, hours before he was to arrive for a regional summit expected to be dominated by talks on security issues and various regional disputes.

Activists began a series of street demonstrations against Trump with a march to the tightly guarded venue of the 31st Association of South-East Asian Nations (ASEAN) summit.

But they were blocked by hundreds of anti-riot police officers more than 1 kilometre away, where they tried to break the barricade but were pushed back.

Shouting anti-US slogans, they carried red banners reading ‘Ban Trump in the Philippines,’ ‘Fight Trump, facism and imperialism!’ and ‘Uphold national sovereignty.’  They later burned at least four flags of the United States and vowed to hold more protests while Trump attends time the ASEAN leaders' summit for the first time.

Trump was also expected to hold a meeting with Phiippine President Rodrigo Duterte. The two leaders met briefly at the Asia-Pacific Economic Conference summit in Vietnam.

US lawmakers have demanded that Trump take up the issue of human rights violations with Duterte.

The Philippine leader said he was confident his American counterpart would not take up the spate of killings related to his campaign against illegal drugs.

At least 3,850 people have been killed in police operations against drug suspects between the time when Duterte came into office on June 30, 2016, and September 16, 2017, according to police data. Police said those killed fought back when arrested.

Aside from those killed in police operations, authorities are also investigating the deaths of nearly 11,000 people to determine if their killings were related to illegal drugs and carried out by hired or vigilante killers.