Yoon Suk-yeol, the presidential candidate of the main opposition party, on Thursday denounced the anti-corruption agency for checking phone logs of his family and dozens of lawmakers from his party.

The day before, the Corruption Investigation Office for High-ranking Officials came under fire over revelations that it had checked phone logs of hundreds of people, including the People Power Party’s presidential candidate and some 80 lawmakers from the conservative opposition party.

“(The CIO) checked the phone records of me, my wife, the friends of my wife and even my younger sister,” Yoon said at the launch ceremony of the party’s regional campaign team in Daegu on Thursday.

“The CIO must be out of their minds.”

Yoon also said CIO chief Kim Jin-wook should be taken into custody for investigation.

In a parliamentary committee plenary session on Thursday, the CIO head denied that his office’s reviews of phone logs were done illegally, and contended that it is an overstatement to say the CIO has conducted unauthorized surveillance.

“We checked the phone records of Yoon three times when the Seoul Central District Prosecutors’ Office looked into it four times. We checked on Yoon’s wife once, and the prosecution inquired for the data five times,” Kim said in the plenary session of the Parliamentary Legislation and Judiciary Committee on Thursday.

The CIO chief also cited data from the Ministry of Science and ICT to explain that the prosecution had inquired with mobile carriers for phone logs some 597,000 times, and the police inquired in 1.87 million cases, but the CIO had checked on only 135 cases in the past year.

Earlier in the day People Power Party Floor Leader Rep. Kim Gi-hyeon also demanded a meeting with President Moon Jae-in.

“As the main opposition party (floor leader), I demand clear measures from President Moon on the CIO’s illegal surveillance and crackdown on the opposition party,” Kim said during a party meeting on Thursday.

Kim Chong-in, the chief of Yoon’s election committee, also demanded Moon weigh in on the controversy.

“Moon had repeatedly said an entity of power should never intervene in politics. But the government is keeping silent on the CIO’s reckless surveillance,” Kim said.

The presidential office, however, refused to comment.

“The CIO is an independent entity and it is not appropriate for Cheong Wa Dae to comment,” a presidential official said Thursday.

As of Thursday afternoon, the CIO had requested Yoon’s phone logs twice in September and once in October, as well as those of his wife once in October, according to the People Power Party.

The CIO also reportedly checked the phone records of 85 People Power Party lawmakers in the National Assembly, and also of nonpoliticians, including some 140 journalists and 30 other individuals, which included lawyers, researchers and their families.

The ruling Democratic Party of Korea has claimed that the CIO’s “surveillance” is just a “normal” part of investigations, and is legal.

Lee Jae-myung, the presidential candidate of the ruling party, said the CIO’s actions did not violate any laws.

“I believe the CIO did it because phone logs provide very important baseline data for any investigation,” Lee said during a press meeting Thursday, adding that it is important not to abuse the access rights.

“It is also important to see whether the CIO had conducted surveillance only on opposition figures. If that is the case, they will have to take responsibility.”

The CIO was officially launched in January, following a push from the Moon administration that said the watchdog would play a role in reforming the country’s prosecution, which has been accused of holding excessive power.

The CIO has the right to indict suspects while looking into corruption among senior officials.

By Jo He-rim (herim@heraldcorp.com)