According to the Yonhap news agency, Woo, who was then a lawmaker from the opposition Democratic Party, had received a total of 10 million won (over $8,900) from a businessman, identified only by the surname Chang, pledging to help Chang's relative to get a job at POSCO, the country's main steel manufacturer.
Since Chang's relative never received the position, the businessman filed a complaint against Woo, accusing him of bribery and fraud. Chang has claimed that Woo had paid the money back to him in 2016, a week ahead of parliamentary elections, out of fear that the businessman would disclose the matter publicly and ruin the diplomat's career.
Woo has denied the allegations, claiming that the money from Chang had been a loan and not a bribe.
The ambassador has launched a complaint against Chang over the false accusations. Prosecutors reportedly plan to question Chang on Wednesday.