Hong of the pro-government Liberty Korea Party said the Democratic Party nominee should be held responsible for what he claimed to be a 113-percent spike in college tuition over the 10 years under the two liberal administrations from 1998-2008.

Moon served as a senior presidential secretary and chief of staff during the late former President Roh's 2003-2008 term.

Hong insisted the liberal candidate and his party acknowledge their wrongdoing in causing the tuition increase in the first place and promise to return it back to the level it was before they first came into power in 1998.

"Under the Lee Myung-bak administration, tuition increased only 3.3 percent and the rise is still being restrained under the incumbent government," Hong said. The conservative Lee administration succeeded Roh's in 2008.

Moon asked if then Hong was against reducing college tuition.

Hong repeated his argument that it will not be a reduction but a return to the normal level.

Hong currently trails Moon and Ahn Cheol-soo of the center-left People's Party. 

Moon returned fire against Hong, asking what he planned to do with dozens of weirs built under the Lee administration's four river renovation project that have been widely blamed for the deterioration of water quality and the spread of green tides in major rivers throughout the nation.

Hong dismissed his claim linking green tides to dammed pools, claiming green algae are in fact largely caused by waste water, agricultural pollutants and weather conditions.

During the debate, front-runner Moon most frequently came under attack by four other candidates that included Yoo Seong-min of the splinter conservative Bareun Party and Sim Sang-jeung of the progressive Justice Party.

Still, it was every candidate against each other as the TV debate marked the sixth and last of its kind before the presidential election slated for Tuesday.

For Yoo, the last TV debate marked an emotional event as it came only hours after 13 of his party's 32 lawmakers quit and declared support for his conservative rival Hong of the former ruling party.

"Today, 13 lawmakers left the Bareun Party. I am tired and lonely, but I am not disappointed. I am not sure what will happen to the Liberty Korea Party after the election, but corrupt conservatives will be destroyed and terminated," Yoo said.

Yoo and 32 other lawmakers who supported the parliamentary impeachment of former President Park Geun-hye had left Park's former ruling party to set up what is now the Bareun Party.

With the departure of the 13 lawmakers that followed the departure of another lawmaker last week, the Bareun Party now controls 19 seats in the 299-seat National Assembly.

The Liberty Korea Party, when and if the former Bareun Party lawmakers are given permission to return, will have 107 parliamentary seats, the second largest number after 119 seats held by the Democratic Party. (Yonhap)