Last month, the prosecution carried out simultaneous raids on around 20 locations, including five universities and the office in charge of operating a private equity fund, over a string of corruption allegations involving his family.

Cho's family is under probe over allegations that its suspected involvement in the fund operation contravenes the ethics law governing public officials.

State prosecutors also raided four universities earlier in the day to probe allegations that his children might have received preferential treatment in gaining admission to elite colleges.

Cho's 28-year-old daughter was listed as the primary author of a pathology paper published in a medical journal in 2008 after she took part in a two-week internship program under a medical professor at Dankook University while she was still in high school.

Critics allege that the paper may have helped her gain admission to Korea University in 2010.

A media report said Monday the prosecution is looking into suspicions that Cho might have been involved in the issuance of alleged false internship certificates for his daughter and a son of the Dankook University professor.

Such documents were issued even though they did not work as interns at an institute of public interest and human rights at Seoul National University, it said. Cho is a law professor of the state university.

The prosecution is also investigating whether similar certificates were published for Cho's 23-year-old son.

The minister denied the allegations, saying that he is "seriously" thinking about taking legal action about what he called a malicious media report.

"As a public figure, I've tolerated many exaggerated reports, but it is hard to accept today's one," Cho told reporters.

He said his daughter participated in the internship program in 2009 and the organization issued the related certificate.

Since being nominated in early August, Cho has been dogged by public outcry and objections from opposition parties due to a series of the scandals.

President Moon Jae-in appointed him despite negative sentiment, saying that if he is not appointed due to unconfirmed suspicions, it would set a bad precedent.

Cho, Moon's former aide, is viewed as the main architect for Moon's vision to reform the prosecution.

During a confirmation hearing in early September, Cho said he will not receive reports from prosecutors over probes into his family if he is appointed. (Yonhap)