Public scrutiny of so-called ghost projects has been intensifying since President Ferdinand Marcos put them centre stage in a July state of the nation address that followed weeks of deadly flooding.

Marcos has since been visiting sites across the country, confirming that some projects marked as completed were non-existent while releasing a list of 15 firms he said held the most contracts.

The owners of both the number two and three firms on that list on Monday released the names of 26 lawmakers and officials from the Department of Public Works and Highways (DPWH) they claimed to have made cash payments to in securing those deals.

"We were continuously used by people in power," business owner Pacifico Discaya II told the Senate hearing.

"We cannot do anything, because if we don't cooperate, they will cause problems for the projects awarded to us," he added.

DPWH officials, engineers and lawmakers would routinely demand cuts ranging from 10 to 25 percent of earmarked funds, he told the Senate.

His business partner and wife, Sarah Discaya, said they made the payments "against our will".

Lawmakers named by the duo had begun issuing denials even before the Senate session had ended.

- 'Deeply rooted' problem -

The DPWH last year touted more than 5,000 ongoing flood control projects, while more than 5,500 had been listed as completed in the two years prior.

Marcos said he was "very angry" about the issue and pledged to create an independent commission to investigate.

"The problem is deeply rooted. I want to know how we come to this," he said in a Sunday podcast.

The Philippine economy lost up to 118.5 billion pesos ($2 billion) from 2023 to 2025 due to corruption in flood control projects, the budget secretary estimated last week.

Michael Henry Yusingco, a senior research fellow at the Ateneo de Manila University School of Government, said regular flooding meant the allocation of funds could "always be justified".

"The flood problem is also a perfect illustration of the failure of governance in our country, right?" he said, noting the country's history of patronage politics.

"It's a perennial occurrence, and yet we are still not able to find the right solutions to it."