Justice Minister Kim Hyun-woong has vowed to put the utmost efforts into investigating irregular election campaign activities during last week's general elections.

"Unsuccessful candidates who violated election law cannot be forgiven for what they have done, nor can winners cover up irregularities they committed," Kim told Yonhap News Agency in an interview on Tuesday.

Regardless of one's political affiliation or position, the minister said he will lead prosecutors to investigate the cases in a fair and prompt manner according to the law.

"Above all, I will make sure those who have been elected through lies and foul play pay the price," Kim said.

The remarks came a week after prosecutors said 104 lawmakers-elect out of the 300-member National Assembly have been booked for charges related to irregular election campaign activities this year.

The number is up 31.6 percent from 79 lawmakers-elect who were booked during the same period in the 2012 parliamentary elections.

The total number of people booked on charges of election-related offenses during this year's general elections reached 1,451, according to data released by the prosecutors. It is up 32.4 percent from that of the previous general elections, which stood at 1,096.

The minister said the methods of election violations have been clearly shifting from bribery to spreading lies.

According to prosecutors' data, some 53.9 percent, or 56 elected politicians, have been caught for negative campaigning, followed by bribery with 22.1 percent. It said 6.7 percent were caught because they used unauthorized methods to sway votes.

"Rumors target unspecified masses, possibly leading to a significant change in the voting results," Kim said, underlining the seriousness of the crime.   

In the latest elections, the main opposition Minjoo Party and the People's Party won 123 and 38 seats, respectively. The ruling Saenuri Party secured just 122 seats, marking the first time in 16 years for a ruling party to fail to win a parliamentary majority. The rest of the seats went to another minor opposition party, the Justice Party, and independents.

Under South Korean law, a fine of more than 1 million won ($863) handed down to lawmakers-elect results in the invalidation of their elections.

During the 2012 general polls, authorities indicted 30 lawmakers-elect until the statute of limitations expired, leading to the invalidation of 10 candidates' elections according to the Supreme Prosecutors' Office. (Yonhap)