Prosecutors raided more than 30 construction firms Wednesday that are suspected of creating slush funds, embezzlement and price-fixing in connection with the four-river refurbishment project under the former Lee Myung-bak administration.

Scores of investigators from two teams at the Seoul Central District Prosecutors’ Office searched the headquarters and local offices of GS Engineering & Construction, Daewoo E&C, SK E&C, Samsung C&T Corp, and POSCO E&C, in Seoul, Gyeonggi Province and South Jeolla Province.

Civic groups have filed six complaints against the firms on charges including creating illegal funds, price collusion and misappropriation.

The firms allegedly embezzled a large sum of the budget by exaggerating the required costs, or receiving money back in cash from subcontractors after they had paid them more than the actual cost.

The prosecutors seized computer hard disks, account books and documents from the offices.

A different department from the prosecutors’ office is conducting an investigation into 12 incumbent and former executives of Hyundai Construction and Engineering, which is accused of hoarding at least 6 billion won ($5.4 million) in slush funds.

In order to dispel public suspicion and environmental concerns over the project, President Park Geun-hye pledged in March that the government would look into the validity of the former government’s river refurbishment plan, in which more than 22 trillion won was spent over five years from 2008.

By Kim Young-won (wone0102@heraldcorp.com)