Journalists from public broadcaster KBS currently on a strike brought to light a bulk of documents showing the government's extensive illegal surveillance on public officials and civilians.
The revelations came through an Internet News program called "Reset" on Thursday.
The journalists said they obtained 2,619 reports drafted by an ethics team under the Prime Minister's Office from 2008 to 2010 after spying on top officials, politicians, businessmen, journalists and civilians.
Other than the results of government inspections and performance evaluations on ministers, deputy ministers and police chiefs, the documents included extensive information on civilians who critized the Lee Myung-bak administration, such as labor union leaders and reporters at various media firms.
For instance, the documents implicated a government intervention in the appointment of presidents of the nation's major TV broadcasters, including KBS and MBC.
Moreover, there was evidence of a grave invasion of privacy.
A report on a high official drafted in 2009 described in minute detail, his illicit love affair.
Both ruling and opposition parties strongly condemned the alleged surveillance.
Calling the case a Korean Watergate scandal, a ranking Democratic United Party lawmaker Park Young-sun said it is now time to impeach President Lee Myung-bak.
The ruling Saenuri Party also called for a thorough investigation into the case, trying to distance itself from the scandal so as not to douse public sentiment before April's general elections.
Meanwhile, the Prime Minister's Office downplayed the documents alleging its illegal surveillance activities Friday, saying that they were already reviewed by the prosecution when the scandal first erupted in 2010.
Kim Yeon-ji, Arirang News.