South Korean opposition to impeach acting president Han

South Korea's main opposition party will submit a bill to impeach acting president Han Duck-soo on Tuesday, a party spokesperson said, increasing the risk of further political uncertainty in Asia's fourth-largest economy.

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

Democratic Party (DP) spokesperson Yoon Jong-kun said on Tuesday the bill, once submitted, is expected to be introduced to a plenary session on Thursday.

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

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

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

Prime Minister Han took over from the suspended Yoon, who was impeached on Dec. 14 and 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," DP's floor leader Park Chan-dae said.

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

With its parliament majority, 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.

Han did not put the bills on the cabinet's agenda on Tuesday, instead calling for the ruling and opposition parties to discuss the bills and other issues together.

An unnamed high-ranking official from Han's office called DP's move "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.

There has been debate between the opposition and the ruling parties over how many votes would be required to impeach Han, in the 300-seat parliament.

Under the constitution, a prime minister can be impeached with just half agreeing, while a president needs two-thirds.

Since the opposition holds a majority in parliament, DP would not need to rely on cooperation from ruling party members if it is half, but if two-thirds are required then it would need the backing of at least eight PPP members.

Parliament speaker Woo Won-shik, who is from the main opposition party, said on Tuesday that the size of the majority needed primarily rests with him, and he would decide after consulting sources such as the National Assembly Research Service.

The research service said just over half is needed to impeach Han, DP lawmaker Kim Han-kyu's office said on Monday.

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

Seok Dong-hyeon, a lawyer helping form Yoon's defense team, 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 prioritizing the Constitutional Court's trial on whether to remove him from office or to reinstate his presidential powers, Seok said.