"All these suspicions have been raised with regard to people that I don't know," he told reporters. "I don't think a civil servant should resign every time such allegations are raised."

There have been growing calls from the opposition political parties for his resignation and an investigation into the allegations that two newspapers have raised. Woo has filed complaints with the prosecution against the newspapers, claiming they made false claims.

On Monday, the local daily Chosun Ilbo reported that in 2011, Korea's leading online game maker Nexon Co. purchased a piece of land in a posh southern district of Seoul, which was owned by the family of Woo's wife.

The report raised the suspicion that Jin Kyung-joon, a senior prosecutor, who was arrested in a bribery case, might have played a role as a broker in Nexon's purchase of the building worth 130 billion won ($113 million).

Nexon's founder Kim Jung-ju, who has been embroiled in a set of corruption cases, is known to be Jin's friend from college. Jin is also known to be close to Woo.

Woo claims that his wife's family sold the real estate asset to Nexon through a "normal" transaction.

A day later, another daily, the Kyunghyang Shinmun, reported that Woo secretly served as an attorney for Jung Woon-ho, former chief of local cosmetics brand Nature Republic. The disgraced businessman has been detained in a lobbying scandal that reportedly ensnared politicians, government officials and prominent figures in the judiciary.

The presidential secretary also denied the allegation that his son, who is currently serving his compulsory military duty as an auxiliary police officer, has been given an easy job because of Woo's status as a presidential aide.

"I brought my son, who had been studying overseas back home, so he could fulfill his military duty," he said. "I have never seen or met his supervisor before," stressing that he never asked for favors. (Yonhap)