A probe by the Board of Audit and Inspection of the Lee Myung-bak administration's massive four-rivers project revealed large-scale corruption in bidding and an attempt by the administration to bring back even more spectacular plans for a cross-country canal.

The canal project was scrapped after a huge public outcry over the potential waste of money, but the BAI on Wednesday said it concluded that the Lee administration then decided to repair the four major waterways as a prelude to reviving the unpopular plan.

It said the initial cost of the four-rivers project was W13.9 trillion (US$1=W1,137) but swelled to W18.3 trillion as the project was implemented with an eye to resuming the grand canal project. It said bidding for the project also caused widespread collusion among builders.

In February of 2009, when Lee publicly abandoned the grand canal project, Cheong Wa Dae secretly ordered the Ministry of Land and Maritime Affairs to develop an alternate plan to revive the project, according to the BAI.

The government then came up with a project to dredge and straighten the country's four major rivers. The amount of dredging gradually expanded from 220 million tons of soil to 570 million tons and from just four sluice gates to 16, with the ultimate aim of building the cross-country canal after all. The costs to the taxpayer spiraled apace.

"If the results of the BAI's probe are true, the nation would have suffered a huge amount of damage," said Cheong Wa Dae spokesman Lee Jung-hyun. "It appears that we will have to get to the bottom of this."

Lee Dong-kwan, who was presidential spokesman during the Lee administration, denied the four-rivers project was an attempt to revive the canal project by the back door.

"We made it clear several times during the Lee administration that the four-rivers project has nothing to do with the grand canal," he said.