Yoon Seok-youl, the presidential nominee of the main opposition People Power Party (PPP), has been booked on additional charges connected to the prosecution's documenting of judges' traits in the past, an activist group said Monday.

The group of self-claimed "judicial justice" activists said it received notification from the Corruption Investigation Office for High-ranking Officials (CIO) on Oct. 22 that Yoon has been booked by the office in connection with its complaint.

The group filed a complaint against Yoon with the CIO in June, alleging that Yoon was responsible for the document, supposedly based on illegal surveillance, and prevented investigations into suspicions surrounding the document when serving as prosecutor general.

In December last year, the justice ministry suspended Yoon, who was then prosecutor general, from duty for two months, citing four counts of alleged misconduct, including the surveillance of judges overseeing politically sensitive cases, including those connected to former Justice Minister Cho Kuk and some presidential officials.

Prosecutors who probed the case, however, dropped the charge against Yoon in February.

Yoon has previously been booked by the CIO in a separate case involving the PPP's political meddling scandal on multiple charges, including abuse of power. He has denied involvement in the case. (Yonhap)