The prosecution is considering expanding its investigation into former President Lee Myung-bak’s four-river restoration project which has been criticized for causing serious environmental damage and budget waste, sources said Sunday.

The Seoul Central District Prosecutors’ Office is planning to launch a joint investigation into allegations that local builders had colluded to win the bids and raise massive slush funds.

A special investigative team is currently looking into a complaint filed by civic organizations that 12 incumbent and former executives of Hyundai Construction and Engineering, one of the builders that participated in the state-led project, allegedly embezzled company funds to create a secret fund. Another team is investigating allegations that 16 former and incumbent executives of construction companies rigged bids to raise their chances of winning project orders.

Separately, the government will launch a task force team next month to begin a full-fledged investigation into the mega-project, an official at the Office for Government Policy Coordination said Sunday. The inspection team will include experts recommended by opposition parties, the official added.

Both plans came a month after President Park Geun-hye ordered a thorough investigation into the case, citing the state auditor’s report that called the project a failure.

“(The government) has to comprehensively check on (the project) to (look into whether there was) budget waste and assuage people’s doubts,” she said during a Cabinet meeting held last month.

The Board of Audit and Inspection’s report in January concluded that the government used unrealistic conditions to estimate how the construction of dams and other facilities would affect water quality. The state auditor also found that 15 of 16 dams showed that the protection of the riverbed had collapsed, and the floodgates at 12 weirs were malfunctioning.

Former President Lee pushed ahead with the 22.2 trillion won ($19.8 billion) project to improve the country’s water management system and prevent the four major rivers ― the Hangang, Nakdonggang, Geumgang and Yeongsangang ― from flooding. The project was among Lee’s major presidential campaign pledges and was carried out within his five years of tenure, despite heavy criticism that it caused environmental damage.

By Cho Chung-un (christory@heraldcorp.com)