Prosecutors on Thursday grilled former presidential secretary over allegations he pressured local food and entertainment giant CJ Group to fire its vice chairwoman.

The prosecution team, looking into the scandal involving President Park Geun-hye's close friend, called in Cho Won-dong to appear as a suspect before the Seoul Central District Prosecutors' Office to answer questions about the suspicions raised.

"I will tell everything to the prosecution," he told reporters before entering the prosecutors' office, declining to further elaborate.

"I feel frustrated," he said, when asked how he feels about the current situation. "I feel personally (embarrassed) to stand here as a person who served as a senior economic secretary when the country was suffering economically."

There have been allegations that Cho, who served as a senior economic secretary to Park from 2013 to 2014, pushed the business group in late 2013 to get rid of Vice Chairwoman Lee Mie-kyung, saying such a move was the will of the president.

Lee was in charge of the conglomerate's entertainment arm, which aired a TV show and distributed a film that were viewed by some conservatives as "leftist." She is known to have remained in the United States since 2014, citing a hereditary disease.

The questioning came three days after investigators raided Cho's home in southern Seoul and confiscated his cell phone, computer hard drives and personal documents.

Earlier on Thursday, Cho was sentenced to six months in prison, suspended for a year, for causing a traffic accident while driving under the influence of alcohol in October last year. Upholding a lower court's decision, the Seoul High Court also found him guilty of refusing to take a sobriety test without any justifiable reason.

Attending the sentencing trial, Cho told reporters he will "tell everything during the prosecution's investigation, without hiding anything," adding, "It does not seem like the right time to (talk about it)." (Yonhap)