South Korea's new President Lee Jae-myung held his first cabinet meeting on Thursday focused on devising an emergency package to address stagnating economic growth and aid households, moving swiftly to start tackling a top campaign pledge.

Lee took office on Wednesday just hours after riding a wave of anger over a brief martial law imposed by Yoon Suk-yeol to win the snap election. The attempt at military rule led to Yoon's ouster and sent shockwaves through Asia's fourth-largest economy.

In brief remarks open to the media, Lee told the cabinet carried over from the caretaker government put in place following Yoon's impeachment in December that there was no time to waste in getting to work as the people were facing hardship.

Lee has so far only nominated a close political ally and legislative veteran as prime minister and is racing to form a cabinet and staff his office to maintain continuity in administration.

The new leader expressed bewilderment on Wednesday after walking into the presidential office to find it stripped of computers, printers and even pens and was quiet like "a graveyard" with government officials who had been assigned there sent back to their posts.

Most of the officials have been ordered back, Lee's spokesperson said on Thursday.

Lee has made economic recovery one of his top priorities and vowed to immediately unleash fiscal spending of at least 30 trillion won to boost growth, which was projected by the central bank in May to be almost half of its earlier estimate this year at 0.8 percent, down from 1.5 percent in February.

Kim Min-seok, whose appointment as prime minister requires parliamentary approval, said on Wednesday the country was facing even more economic turmoil than during the Asian financial crisis of 1997, complicated by unfavourable external factors.

"Today, the economy is heading downward and stagnating, which is why I believe it's much more difficult," he said.

The previous government had made little progress in trying to assuage crushing US tariffs that would hit some of the country's major export-reliant industries, including autos, electronics and steel.

Lee faces what could be the most daunting set of challenges for a South Korean leader in decades, analysts said, ranging from healing a country deeply scarred by the martial law attempt to tackling unpredictable protectionist moves by the United States.

On Thursday, Lee withdrew the nomination of two judges to the Constitutional Court, made by acting president Han Duck-soo before the election, his office said.

Lee has said Han had no power to nominate judges as an unelected acting leader.

The ruling Democratic Party-controlled parliament also passed on Thursday special counsel acts to investigate former president Yoon on insurrection charges and his wife Kim Keon-hee over corruption allegations.

The party had previously passed the special counsel acts on multiple occasions, but they were repeatedly vetoed by Yoon and then the acting president.

Yoon is currently facing a separate trial on insurrection charges. (Reuters)