An effigy of South Korea's impeached President Yoon Suk Yeol is seen in a mock prison as protesters take part in a rally calling for Yoon's ouster in front of the Gwanghwamun Gate of Gyeongbokgung Palace in Seoul on December 21, 2024. Jung Yeon-je, AFP

SEOUL, South Korea -- Protests were planned across South Korea on Saturday, as supporters and opponents of suspended president Yoon Suk Yeol prepared to hold rival rallies two weeks after he was impeached.

Vast protests both for and against Yoon have rocked South Korea since he sought to impose martial law in early December, plunging the country into its worst political crisis in decades.

Lawmakers on Friday impeached Yoon's replacement, acting president Han Duck-soo, after he refused demands to complete Yoon's impeachment process and to bring him to justice.

It is up to the Constitutional Court to decide Yoon's, and now Han's fate, but demonstrators from both camps have vowed to keep up pressure in the meantime.

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"Nearly two million people will come together to protect president Yoon," said Rhee kang-san, a supporter of Yoon who is one of the rally organizers in Seoul.

"The rally continues our efforts to amplify the people's voice against impeachment."

An organiser of a rival anti-Yoon rally said the anger of those who supported his impeachment was "burning even more intensely".

"The people are now strongly demanding Yoon's immediate dismissal and punishment," she added.

At the heart of the backlash against Han was his refusal to appoint additional judges to the Constitutional Court, which has three vacant seats.

While the six current judges can decide whether to uphold parliament's decision to impeach Yoon, a single dissenting vote would reinstate him.

The opposition wanted Han to approve three more nominees to fill the nine-member bench, which he had refused to do, leaving both sides in deadlock.

The second impeachment on Friday thrust Finance Minister Choi Sang-mok into the roles of acting president and prime minister.

It also took the country into uncharted territory.

READ: South Korean president fails to appear before corruption watchdog

"We've had an acting president before," said Lee Jun-han, a professor at Incheon National University. "But this is the first time we've had a substitute for a substitute."

Choi said in a statement after the impeachment that "minimising governmental turmoil is of utmost importance at this moment," adding that "the government will also dedicate all its efforts to overcoming this period of turmoil".

Like Han, Choi will face pressure from the opposition to accept the appointment of new judges.

If he refuses, he could face his own impeachment vote.

© Agence France-Presse