South Korea's first lady Kim Keon Hee has been questioned over allegations of stock manipulation and graft involving a $2,200 luxury handbag, the prosecution said on Sunday. 

The questioning comes as the opposition calls for a special probe into the first lady, who has been under scrutiny for accepting a Dior bag in violation of government ethics rules, and for her alleged role in a stock manipulation scheme.

Prosecutors conducted "face-to-face questioning" of Kim on Saturday, the Seoul Central District Prosecutors' Office said in a statement. 

Hidden camera footage released last year appeared to show Kim accepting a $2,200 luxury designer handbag, an act that was later dubbed the "Dior bag scandal" by local papers. 

The scandal hit President Yoon Suk Yeol's already-low approval ratings, contributing to a stinging defeat for his party in general elections in April as it failed to win back a parliamentary majority.

Such a gift would violate South Korean law, which bans public officials and their spouses from accepting anything worth more than $750. 

Kim's aide told investigators earlier this month that the first lady told her to return the bag on the same day she had received it, but she had forgotten to, according to Yonhap news agency. 

In his first remarks on the bag scandal in February, Yoon dismissed it as a "political scheme" and said his wife had accepted the bag only because it was difficult for her to refuse it. 

But he later apologized in a rare press conference in May, describing his wife's acceptance of the bag as "unwise". 

It is not the first time Kim has faced public scrutiny. During Yoon's presidential campaign, she was forced to apologize over falsified credentials.