The Seoul metropolitan government on Wednesday announced a plan to launch a probe into allegations of sexual abuse by the city's late mayor raised by his former secretary.

Park Won-soon, the city's three-term mayor, was found dead in the hills of a Seoul mountain in the early hours of Friday after hundreds of police and rescue officials searched for him following a missing persons report. A handwritten note, saying "sorry," was later found in Park's study.

His abrupt death came a day after a former secretary filled a complaint with the police. On Monday, civic groups and her attorney held a press conference where they claimed the public servant suffered unwanted physical contact and received inappropriate messages from Park for over four years.

The city said it will establish a joint investigative team involving women rights and human rights groups, along with legal experts, for the case "to guarantee fairness and objectivity."

"Seoul city will strive to strictly get down to the truth through a joint investigative committee involving external experts, such as womens rights groups, human rights experts and legal experts. By forming and running the joint committee, (the city) will guarantee the fairness and objectivity of the probe," city spokesperson Hwang In-sik told reporters.

Hwang did not elaborate on the scope or size of the committee, including whether the city's gender and human rights departments and the civic groups that represented the secretary will take part.

"The city's value is that fairness and objectivity should be prioritized ... we will decide on a level and scope that both sides can accept after sufficient consultations with women rights and human rights groups," Hwang added.

A detailed schedule for the investigation was not immediately provided.

The city said its priority will be to prevent any "secondary damages" inflicted on the former secretary and provide all possible support measures to help her recover.

Hwang said the city will provide "valid, sufficient and maximum" support to the alleged victim, including therapy sessions with psychologists and safety measures for the former secretary's residence.

Cheong Wa Dae officials refrained from commenting directly on the sensitive case, apparently seeking to maintain distance from political controversies.

Asked about President Moon Jae-in's response to the allegations involving the late mayor, a Cheong Wa Dae official told reporters that, "We can't make public every remark of the president."

Now that the Seoul city government has announced a plan for the joint probe, "It's time to calmly wait and see its results," he added, speaking on the condition of anonymity.

Cheong Wa Dae earlier issued a statement that there shouldn't be any second victimization of the accuser, the official said.

Public calls have grown for a formal investigation into the incident, which women rights groups labeled as a typical instance of workplace sexual abuse involving a disparity in power.

Lee Mi-kyoung, who leads the Korea Sexual Violence Relief Center, stressed how the victim was "unable to decline or defy the mayor, as a secretary" and that her request for help fell through as most in the city government told her it must have been a "mistake" or that "it's part of a secretary's job to emotionally support the mayor."

"(We're facing) a situation in which the defendant has become absent ... but that doesn't mean the truth disappears," said Ko Mi-kyung, head of the Korea Women's Hot Line, one of the organizations that co-hosted the press conference on behalf of the victim, demanding a "proper probe" into the case.

Politicians, from both the ruling and main opposition parties, have also urged the city government to launch an investigation.

"As the party's chairman, I feel miserable, and I have no words for the citizens. I again deeply express my apology to the citizens," Democratic Party Chairman Lee Hae-chan said earlier in the day, asking the city government to launch a probe.

The planned probe, however, is expected to face challenges as its conclusion is not legally binding.

An ongoing police investigation is reportedly only focusing on Park's itinerary and the cause for his apparent suicide.

The national human rights commission, meanwhile, has also opened a probe into the case after a civic group filed a complaint about it. (Yonhap)