South Korea’s main opposition party vowed on Tuesday to impeach acting president Han Duck-soo but reversed an earlier plan and decided to wait until later in the week, party officials said, as the risk of further political uncertainty heightened.

The move comes as the country is reeling from impeached President Yoon Suk Yeol's short-lived bid to impose martial law on December 3 that he partly blamed on the opposition's propensity to impeach government officials.

Opposition Democratic Party (DP) floor leader Park Chan-dae said the party will wait until later this week to decide whether to go ahead with the plan to impeach Han. Earlier, the party said it would introduce a bill to impeach Han on Tuesday.

The DP, which has a majority in parliament, is taking the step after Han postponed signing legislation to launch a special counsel investigation into President Yoon Suk Yeol's failed bid to impose martial law.

It said Han was acting against the will of the people, effectively aiding Yoon, whose powers have been suspended after parliament voted to impeach him on December 14.

Once an impeachment bill is submitted then formally introduced at a plenary session, it must be voted on within 24 to 72 hours.

If Han is impeached, the finance minister would be next in line to lead the government as acting president, according to South Korean law.

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Prime Minister Han took over from the suspended Yoon, who faces a Constitutional Court review on whether to oust him or restore his powers.

“Acting president Han made it clear at today's cabinet meeting that he would not greenlight the special prosecution law,” the DP's Park said.

“There is no way to interpret it other than that he is delaying time.”

With its parliamentary majority, the DP passed bills this month to appoint a special counsel to pursue charges of insurrection, among others, against the conservative Yoon, and to investigate his wife over a luxury bag scandal and other allegations.

An unnamed high-ranking official from Han's office called the DP’s move to impeach Han “highly regrettable”, the Newsis news agency said.

“The international community is currently supporting the acting president system ... Impeachment could undermine that trust, and adversely affect the economy,” Newsis cited the official as saying.

Han’s office could not immediately be reached for comment.

Yoon’s ruling People Power Party (PPP) has accused the DP of threatening to topple the government for not complying with their demands, at a time when South Korea’s key ally the United States has just restarted planned communications with the country under Han's stewardship.

Yoon has yet to announce his legal team or appear publicly since a televised statement on December 14, the day parliament impeached him.

Seok Dong-hyeon, a lawyer advising Yoon, told reporters on Tuesday that Yoon is unlikely to appear for questioning on Wednesday, Christmas Day, in answer to a summons by authorities investigating his move to impose martial law.

Yoon is prioritising the Constitutional Court's trial, Seok said.