"She said she is sorry for causing confusion in the country but declined to specifically comment on what she did wrong," said Rep. Kim Han-jung of the main opposition Democratic Party.

The committee earlier said it decided to file complaints against the three defendants on charges of contempt of the National Assembly.

Choi's lawyer Lee Kyung-jae said in a press release that such an attempt to interrogate Choi in the detention facility goes against the law and the Constitution. 

"The committee does not have the authority to question a witness who did not attend the hearing," he said. "If they wanted to question the defendant, they should have sent a request seeking her appearance at least seven days earlier, according to the law."

A justice ministry official, who asked not to be named, meanwhile said an interrogation in a detention center is possible under the law and other rules.

The panel has held five sessions of inquiry, summoning presidential staff members, business tycoons and other figures involved in the influence-peddling scandal.

During an interrogation by special prosecutors Sunday, Choi denied new allegations that she stashed around 10 trillion won abroad. She told investigators that she would donate all the money to the state, if there were any such money, according to the independent counsel team.

Local media reported Choi may have hidden 800 billion won in Germany and more in other European countries via her ghost companies.

The independent counsel on the scandal said the team has hired a former state tax agency official to trace Choi's assets at home and abroad.

Sources said that the team will also track down dubious assets Choi's family has amassed over the past 40 years.

Choi is the fifth daughter of Park's late mentor Choi Tae-min. The late Choi, who used to lead a religious cult, had reportedly advised Park since her mother, Yook Young-soo, was assassinated by a North Korea sympathizer in 1974. (Yonhap)