President Park Geun-hye accepted the resignation of Prime Minister Lee Wan-koo on Monday, a week after he offered to quit amid snowballing allegations that he received illegal political funds from a deceased businessman.
The announcement came hours after the president returned from her trip from South America. Lee's farewell ceremony was held later in the evening.
The president, however, remained silent on the graft scandal, with her office explaining she would need a day or two of rest after falling ill during her Latin American tour last week. Park has been facing mounting calls to state her position over the scandal.
The president returned from the 12-day trip Monday morning, but has been suffering from a sore throat and abdominal pain, her spokesperson Min Kyung-wook told reporters.
Presidential medical staff have advised rest for one or two days for what is apparent "overwork," Min added.
"Adnominal pain caused by stomach cramps due to chronic fatigue was her major symptom," he said. "The president's health condition was not good (during the trip), as she also had a mild fever caused by pharyngitis," he said, adding that Park powered through her schedule, despite her bad health.
Min said the office would announce her forthcoming schedules and her "position" on the looming political crisis in due time, stressing her health is "the top priority."
Park was expected to preside over the weekly Cabinet meeting Tuesday, but she chose not to attend the meeting, according to officials.
With the prime minister leaving the office, Finance Minister Choi Kyung-hwan, who serves as deputy premier, would chair the meeting this week, they said.
Lee was one of eight political heavyweights alleged to have accepted illegal political funds from deceased ex-Keangnam chairman Sung Woan-jong.
Park last week expressed regrets over the prime minister's resignation, saying it must have been a tough decision for Lee to step down from the post.
Park appointed Lee, a veteran politician and former Saenuri floor leader, in February as part of efforts to seek momentum in her reform drive.