By Ju-min Park and Tony Munroe
SEOUL (Reuters) - A tearful and apologetic South Korean President Park Geun-hye said on Friday her "heart was breaking" over a political scandal that has engulfed her administration, pledging to cooperate with prosecutors in their investigation.
Park has been rocked by an influence peddling scandal involving an old friend, sending her approval rating to just 5 percent, a 12 percentage point drop from last week and the lowest since such polling began in 1988, according to a Gallup poll released on Friday.
In a brief televised address to journalists, Park said that prosecutors should clarify what happened and that everyone involved should be held accountable, including herself, and take responsibility if found guilty.
"It is hard to forgive myself and sleep at night with feelings of sorrow," Park, 64, said, her voice trembling.
A prosecution official declined to comment to Reuters when asked if Park would be subject to investigators' questioning, which would be a first for a sitting South Korean president.
The leader of the main opposition party said Park's apology was insincere.
"The president should remove her hands from state affairs," Choo Mi-ae, leader of the Democratic Party of Korea, said in a statement, stopping short of demanding Park's resignation.
Park has faced growing pressure from the public and political opponents to resign. No South Korean president has ever failed to finish their five-year term.
A group of civic organizations has planned a large street protest for Saturday evening demanding that Park step down.
A former Park aide, Jeong Ho-seong, was arrested late on Thursday on suspicion of leaking classified information, a prosecution official told Reuters, the second member of Park's former inner circle of advisers to be arrested this week.
Prosecutors asked a court to grant an arrest warrant for another former adviser, An Chong-bum, on suspicion of abuse of power and attempted extortion, a prosecutor said, declining to elaborate. An has been under emergency detention since Wednesday.
Park's long-time friend, Choi Soon-sil, 60, is alleged to have used her closeness to the president to meddle in state affairs, and her lawyer has said he expects prosecutors to look into whether she inappropriately received classified documents and benefited unlawfully from two non-profit organizations.
"It is very miserable and regrettable that a particular individual is said to have taken profits and committed several unlawful acts, while we are working on a job in hopes of helping the national economy and people's lives," Park said, referring to Choi.
Park closed her remarks with a bow and walked towards a row of journalists and repeated her apology. She did not take questions.
"I think she'll manage to regain a bit of sympathy from the people who used to like her, but the speech itself was not enough to fix the crisis at hand," said Kim Man-heum, head of the Korea Academy of Politics and Leadership, a research organization.
Park acknowledged carelessness in her ties with Choi, who Park has said helped her through difficult times.
"It is true that I lowered the wall of caution myself because she stood by me in the most difficult period in my life," Park said.
"I've already cut all the connections in my heart but from now on will completely break my private connections."
Their friendship dates to an era when Park served as acting first lady after her mother was killed by an assassin's bullet intended for her father, then-president Park Chung-hee. Five years later, in 1979, Park's father was murdered by his disgruntled spy chief.
REJECTS CULT CLAIMS
Choi, who has been in custody since Monday, told South Korea's Segye Ilbo newspaper last week that she received drafts of Park's speeches after Park's election victory but denied she had access to other official material, influenced state affairs or benefited financially.
Choi's late father, Choi Tae-min, headed a now-defunct religious sect and was also close to Park during and after her father's presidency.
A 2007 U.S. diplomatic cable described the senior Choi as the "Korean Rasputin", an allusion to a close adviser to the last tsar of Russia and the perceived influence over Park Geun-hye.
Choi Soon-sil has been portrayed in Korean media as having inherited her father's influence over Park, while local media have also characterized Choi Tae-min's religious group as a cult and alleged that Park held a shamanistic ritual at the presidential compound.
Park rejected those allegations.
"There is even talk that I fell into a cult or I held a shamanistic ritual at the Blue House," she said. "I am saying clearly: none of this is true."
(Reporting by Tony Munroe, Ju-min Park, Christine Kim and Se Young Lee; Editing by Nick Macfie)