SEOUL: South Korea's three opposition parties said they would file an impeachment motion Friday against beleaguered President Park Geun-Hye, and push for a national assembly vote next week.
Accused of colluding with a close friend who faces embezzlement charges, Park said last week she would be willing to step down in the face of weekly mass protests that have seen millions take to the streets of Seoul and other cities.
The opposition said Park's offer, which put the manner and timing of her resignation in the hands of parliament, was an effort to buy time and avoid impeachment.
The joint opposition commands the most seats in the legislature, but would need the support of nearly 30 members of Park's Saenuri Party to secure the two-thirds majority needed to impeach the president.
"We've agreed to actively persuade anti-Park (Saenuri) lawmakers to back us," said Park Jie-Won, parliamentary floor leader of the opposition People's Party.
If passed, the motion would go to the Constitutional Court for approval -- a process that could take up to six months.
The Saenuri Party has called on Park to stand down voluntarily in April next year, allowing a presidential election to be held in June -- six months ahead of schedule.
Party officials have given her a week to accept the timeline or face impeachment.
The scandal engulfing Park's administration is centred around a long-time friend of the president, Choi Soon-Sil, who has been dubbed "Korea's Rasputin".
Prosecutors say they have evidence that Park colluded in Choi's efforts to coerce firms to "donate" tens of millions of dollars to foundations she set up for personal gain.
Park has been named as a formal suspect in the investigation, making her the first sitting president to be subject to a criminal probe while in office.
While she retains the presidency, Park cannot be charged with a criminal offence except insurrection or treason, but she would lose that immunity once she steps down.
Massive weekly protests have been intensifying over the past month, with organisers claiming up to 1.5 million people braved freezing temperatures in Seoul last Saturday to demand Park's resignation.
Activists have called for a sixth protest this Saturday in central Seoul, despite Park's announcement that she would be willing to cede power.
Park on Wednesday approved a lawyer recommended by the opposition-controlled parliament as an independent prosecutor.
The special prosecutor will interview the president and be given 120 days to follow up on the findings of state investigators.
Park has backtracked on earlier promises to make herself available for questioning in a judicial probe.