Thousands of protesters in the Philippine capital expressed their outrage over a corruption scandal faced off with police on Sunday in tense scenes.

The scandal involves lawmakers, officials and businesspeople who allegedly pocketed huge kickbacks from flood-control projects in the poverty-stricken and storm-prone Southeast Asian country.

Police forces and troops had been put on alert to prevent any outbreak of violence.

Thousands of police officers were deployed to secure separate protests in a historic Manila park and near a democracy monument along the main EDSA highway, also in the capital region, where organizers hoped to draw one of the largest turnouts of anti-corruption protesters in the country in recent years.

The United States and Australian embassies issued travel advisories asking their citizens to stay away from the protests as a safety precaution.

Organizers said protesters would focus on denouncing corrupt public works officials, legislators and owners of construction companies, along with a system that allows large-scale corruption, but they would not call on President Ferdinand Marcos Jr. to step down.

Marcos first highlighted the flood-control corruption scandal in July in his annual state-of-the-nation speech.