Seoul (AFP) - South Korean lawmakers pushed to impeach President Yoon Suk Yeol in the early hours of Thursday, accusing him of declaring martial law to stop criminal investigations into himself and his family.

Yoon’s declaration of South Korea’s first martial law in more than four decades was swiftly overturned by lawmakers in scenes of high drama, but it has plunged the country into turmoil and alarmed allies.

The future of Yoon, a conservative politician and former star public prosecutor elected president in 2022, now looks highly uncertain.

Opposition lawmakers had jumped fences and tussled with security forces to get into parliament and vote down the martial law overnight Tuesday to Wednesday, and they then filed a motion to impeach Yoon.

The motion says Yoon “violated the constitution and the law” and accuses him of imposing martial law to evade investigations “into alleged illegal acts involving himself and his family”.

In an early Thursday morning session, lawmakers presented the impeachment motion to parliament.

“This is an unforgivable crime – one that cannot, should not, and will not be pardoned,” MP Kim Seung-won said.

Yoon’s action took allies by surprise, with the United States, which has nearly 30,000 troops in the country, saying it had no prior notice and voicing relief at his reversal.

“South Korea’s democracy is robust and resilient, and we’re going to continue to speak out publicly and engage privately with South Korean counterparts to reinforce the importance of that continuing,” US National Security Advisor Jake Sullivan said Wednesday.

- ‘Tragic’ -

Under South Korean law, the motion must be voted on between 24 and 72 hours after it is presented to a parliamentary session, according to Yonhap news agency.

Yoon’s prospects look bleak – the opposition holds a large majority in the 300-member legislature and needs only a handful of defections from the president’s People Power Party to secure the two-thirds majority needed to pass the motion.

The main opposition Democratic Party has also filed a complaint of “insurrection” against the president, ministers and top military and police officials – which can carry a penalty of life imprisonment or even death.

In a show of public anger, thousands of protesters converged around Yoon’s office in Seoul late Wednesday after staging a rally in Gwanghwamun Square, demanding his resignation.

Even the leader of Yoon’s own ruling party described the martial law attempt as “tragic”. But party lawmakers have decided to oppose the motion to impeach Yoon, Yonhap reported.

One lawmaker from the opposition Rebuilding Korea Party said they had not yet decided when a vote on the motion would take place, the agency said.

- ‘Push out Yoon’ -

In his television announcement imposing martial law late Tuesday, Yoon cited the threat of North Korea and “anti-state forces”.

More than 280 troops, some flown in by helicopter, arrived at parliament to lock down the site.

But 190 lawmakers defied armed soldiers to force their way into the building to vote against the move.

The constitution says martial law must be lifted when a parliamentary majority demands it, leaving Yoon with little choice but to retract his decision and call off the military in another televised address six hours later.

Senior aides to Yoon offered to resign en masse, as did the defence minister, who said he took “full responsibility for the confusion and concern” around the martial law declaration.

Yoon has yet to publicly reappear.

The repeal of martial law prompted jubilation among flag-waving protesters outside parliament.

As night fell in Seoul Wednesday, protesters again demanded Yoon step down.

“I was so incensed I couldn’t sleep a wink last night, I came out to make sure we push out Yoon once and for all,” 50-year-old Kim Min-ho told AFP.

- North Korea ‘threat’ -

Yoon had said martial law was needed to “safeguard a liberal South Korea from the threats posed by North Korea’s communist forces and to eliminate anti-state elements”.

Yoon did not elaborate on the North’s threats, but the South remains technically at war with nuclear-armed Pyongyang.

The president also labelled the Democratic Party as “anti-state forces”.

In recent weeks, Yoon and his party have been at odds with the opposition over next year’s budget.

His approval rating dropped to 19 percent in a Gallup poll last week, with voters angry over the economy as well as controversies involving his wife.