Ruling People Power Party floor leader Joo Ho-young, left, gives opening remarks during a party response meeting at the National Assembly, Oct. 18. Yonhap

The ruling People Power Party (PPP) on Tuesday stepped up pressure on former President Moon Jae-in to comply with investigations into his administration's handling of the 2020 death of a fisheries official at the hands of North Korea.

A prosecution investigation into the case has led to prosecutors seeking arrest warrants for former Defense Minister Suh Wook and former Coast Guard Commissioner General Kim Hong-hee on charges related to the Moon administration's conclusion without sufficient evidence that the official was killed while attempting to defect to the North.

Moon is not subject to the prosecution investigation.

But the state auditor, the Board of Audit and Inspection, is also looking into the case, and earlier this month, the agency asked Moon to answer questions in writing, but he rejected the request, denouncing it as "disrespectful."

Moon's main opposition Democratic Party of Korea has denounced the investigations as political reprisal.

"Rather than shamelessly crying foul against what they claim as a political suppression, the main opposition should at least bow its head and apologize to the bereaved family of the killed public servant," PPP Rep. Yang Kum-hee said in a statement in response to a press conference by main opposition Democratic Party of Korea (DPK) lawmakers in front of the presidential office a day earlier.

Former President Moon Jae-in waves toward his supporters at his private retirement home in Yangsan, South Gyeongsang Province, July 23. Newsis

"Former President Moon Jae-in should especially be held responsible," the lawmaker said, denouncing Moon's decision to not comply with the state auditor's request for a written probe and stressing that there will be "no exception" in the prosecution's probe of the case.

Wrapping up a two-month investigation into the Moon administration's handling of the official's death near the Yellow Sea border last week, the Board of Audit and Inspection (BAI) has requested the prosecution to investigate 20 people on charges that include power abuse and document forgery.

The list reportedly includes top security officials of the Moon administration, such as former National Security Adviser Suh Hoon, former National Intelligence Service chief Park Jie-won and former Defense Minister Suh Wook.

The PPP's statement released Tuesday is the latest in what appears to be its push to hold the liberal bloc accountable over security-related incidents amid North Korea's intensifying nuclear threat.

PPP heavyweights like Reps. Kim Gi-hyeon and Kweon Seong-dong have called for a probe into the former president, claiming his administration sided with the North over the fisheries official's death.

PPP chief policymaker Rep. Sung Il-jong slammed the DPK for failing to hold the North in check as it recently pushed ahead with a series of missile provocations.

"It is the DPK regime that helped North Korea's nuclear armament," Sung said the previous day, accusing it of "policy failure" that prompted the recent provocations. "There are no longer many people who will be deceived by the DPK's propaganda."

The main opposition party denounced the PPP for exploiting security issues with political intentions. (Yonhap)