Police and protesters have engaged in scattered clashes as tens of thousands of people demonstrated in the Philippine capital, Manila, angered over a corruption scandal involving flood control projects that are believed to have cost billions of dollars.

With organisers hoping to draw one of the largest turnouts at anticorruption protests, police and soldiers were put on alert on Sunday to prevent possible outbreaks of violence. At least 17 people who threw rocks at riot police and set fire to the tyres of a barricade were arrested.

Less than an hour later, police used a water cannon on another group of masked protesters. According to the AFP news agency, some police picked up rocks and threw them back at demonstrators. Manila Mayor Francisco Isko Moreno Domagoso said police officers were wounded in clashes with protesters and were receiving medical treatment.

“Manila CDRRMO [City Disaster Risk Reduction Management Office] and Manila Health Department gave first aid to our policemen deployed in Mendiola today,” he wrote on Facebook. “They were rushed to the nearest district hospital, the Sampaloc Hospital so that they can be treated by our doctors. Let’s maintain order and peace in our city. Let’s all be careful.”

There has been violence recently at protests in another Southeast Asian nation, Indonesia, where demonstrators, infuriated by police violence, parliamentarians’ wages and soaring inflation, have been staging nationwide rallies.

Protesters in Manila earlier waved Philippine flags and held a banner that read, “No more, too much, jail them,” as they marched, demanding the prosecution of all those involved in corruption.