The infrastructure scandal has prompted a series of protests across the capital Manila in recent weeks, including one involving about 3,000 students at the University of the Philippines campus.

While most demonstrations so far have largely been small-scale, an annual protest tied to the 1972 declaration of martial law by Marcos's father is expected to draw large crowds on Sunday.

The Southeast Asian nation's army has been placed on "red alert" as a precaution.

At a Monday press briefing where he named a former Supreme Court justice head of an investigatory body, Marcos said the public's anger was justified.

"To show that you are enraged, to show that you are angry, to show that you are disappointed, to show that you want justice... What's wrong with that?" Marcos said at at a press briefing.

"I don't blame them. Not one bit".

He also reiterated a pledge that friends and allies "would not be spared" when quizzed about his cousin, House Speaker Martin Romualdez, whose name was brought up by witnesses at hearings into the scandal last week.

Romualdez, who has denied any involvement, is one of numerous lawmakers placed in the spotlight by the widening scandal.

- Hearings -

Last week, the owners of a construction firm accused nearly 30 House members and Department of Public Works and Highways (DPWH) officials of taking cash payments.

Marcos on Monday announced former Supreme Court justice Andres Reyes would head a three-person commission tasked with looking into the past 10 years of flood control projects.

While the body will have the power to conduct hearings and review evidence, they are not authorised to unilaterally levy punishments.

The Philippines has a long history of scandals involving public funds, in which high-ranking politicians found guilty of corruption have typically escaped serious jail time.

The Department of Finance has estimated that the Philippine economy lost up to 118.5 billion pesos ($2 billion) from 2023 to 2025 due to corruption in flood control projects.

Vince Dizon, an economist and political aide under multiple administrations, earlier this month took the reins of the DPWH, whose reputation has taken a severe hit.

On Monday, he dismissed three agency officials in Bulacan province north of Manila, long-plagued by flooding, for misconduct and gross neglect of duty.