Choi Soon-sil (C), who is involved in a political scandal, reacts as she is surrounded by the media upon her arrival at a prosecutor's office in Seoul, South Korea, October 31, 2016. [Photo/Agencies]

SEOUL - The woman at the centre of a political scandal that has cast the South Korean presidency into crisis was detained late on Monday, Yonhap News Agency reported, hours after she had arrived at the office of local prosecutors to answer questions.

Prosecutors are investigating allegations that Choi Soon-sil used her friendship with President Park Geun-hye to influence state affairs by gaining access to classified documents and benefited personally through non-profit foundations, a prosecution official said earlier.

Worried that Choi may be a flight risk and could destroy evidence, prosecutors placed her under emergency detention without a warrant, Yonhap reported, citing a prosecution official.

She was taken to a Seoul detention facility, Yonhap said.

Prosecutors and Choi's lawyer were not immediately available for comment early on Tuesday morning.

Under South Korean law, a suspect can be held under emergency arrest without a warrant for up to 48 hours. A longer detention requires an arrest warrant issued by a court.

Choi begged forgiveness when she arrived to meet prosecutors earlier on Monday.