A ranking Seoul prosecutor requested an internal inspection into himself Tuesday after allegations arose that he had ordered his subordinates to tone done their ongoing investigation into a high-profile election meddling scandal involving the state intelligence agency.

The move comes a day after a senior prosecutor, who formerly headed the investigation team into the scandal, testified during a parliamentary audit that Cho Young-kon, the head of the Seoul Central District Prosecutors' Office, has pressured the team to not aggressively pursue the probe.

Cho rejected the claim, saying that the prosecutor, Yoon Seok-youl, was dismissed from the team as he had failed to report to his bosses before pressing additional charges in the case.

Cho asked the Supreme Prosecutors' Office to launch the formal inspection, the official said, adding that the prosecution office will first hold a meeting to review whether the inspection is needed.

It marks the first time any senior prosecutor has made such a request.

The National Intelligence Service (NIS) has been probed over allegations that it launched an online smear campaign to sway public opinion in favor of President Park Geun-hye, the then ruling party candidate, and slander the main opposition Democratic Party's candidate, Moon Jae-in, ahead of the December election.

The prolonged scandal has been brought back into the spotlight again after the prosecution raised fresh allegations last week that NIS agents posted more than 55,000 political messages on Twitter before the poll.

Attention is now focused on whether a Seoul court will allow the prosecution to press additional charges against Won Sei-hoon, the former NIS direct, who is standing trials. (Yonhap News)