Ex-president Park Geun-hye's friend Choi Soon-sil has reacted with dismay to the ouster of her longtime protector, making a confused stab at an apology in her corruption and influence-peddling trial on Monday.

"I am so sorry to the public that we are sitting here as part of the corruption scandal," Choi told the Seoul Central District Court while questioning a witness. "I am very perplexed."

Choi is being tried on charges that she colluded with Park and two former Cheong Wa Dae aides to extort billions from major conglomerates. Choi made the remarks when given the opportunity to question a witness in the trial, former vice culture minister Kim Chong, whom she is accused of levering into office to smooth her path.

Korean courts allow defendants to question witnesses. But Choi continued to insist that neither she nor Park sought to profit privately from corporate donations to the dubious Mir and K-Sports foundations she established.

She asked Kim if she had ever made a request to him seeking personal gain and added she is "frustrated" by the accusation that she meddled in government business to enrich herself.

The former vice culture minister fought back tears as he said, "I feel used by the [former] president and Choi. I apologize to the public and am distraught."