Updated

A lawyer for the jailed woman at the center of the biggest South Korean political scandal in decades said Thursday that prosecutors threatened to "annihilate" her family and used other abusive language during questioning.

Prosecutors denied the accusations and expressed strong regret over them.

The woman, Choi Soon-sil, a longtime friend of President Park Geun-hye, has been arrested for allegedly interfering in state affairs and extorting money from businesses. Park was impeached last month over the scandal and the Constitutional Court is reviewing whether to formally end her rule.

Choi created a stir Wednesday by shouting out accusations about prosecutors when she was brought to the office of prosecutors. Choi screamed out to reporters that the investigation was unfair and said she had been forced to confess untrue things about her relationship with Park.

There is huge pressure on prosecutors amid widespread fury in South Korea over the charges against Choi and Park. Millions of South Koreans have taken to the streets to protest what prosecutors have described as collusion with Park that allowed Choi to pull government strings from the shadows.

But on Thursday, her lawyer accused prosecutors of questioning Choi without informing him late on Christmas Eve in what he called a violation of a law that guarantees the right to counsel.

During questioning that he said lasted until 1 a.m. on Christmas Day, the lawyer, Lee Gyeong-jae, said prosecutors used "very shocking" language that abused Choi's human rights. He said they threatened to "annihilate" Choi's family and make "Choi and even her grandson live (in shame) so that they cannot hold their faces up."

Lee said the threats to destroy a person's family was similar to the feudal language used during the Joseon Dynasty, which ruled the Korean Peninsula for 518 years before it was colonized by Japan in 1910.

Lee accused prosecutors of trying to induce Choi to confess to things she had not done.

His conference was disrupted at the last minute with a middle-aged woman shouting and urging him not to speak in defense of Choi. "Do you think she should be treated well while being investigated?" the woman shouted.

The office of special prosecutors investigating the scandal said later Thursday that one of their senior prosecutors met Choi on Christmas Eve for an informal interview but did not use any of the abusive language cited by Choi's lawyer.

Spokesman Lee Kyu-chul said prosecutors have not tried to induce Choi into making any false confessions. Lee said Choi's lawyer was told in advance of the Dec. 24 meeting and that it did not last until the next day.

Prosecutors said Wednesday they plan to question Park and search her office by early next month. Park has said she would cooperate with the investigation.