SEOUL — South Korea's President Yoon Suk Yeol ordered the arrest of his own ruling party's leader Han Dong-hoon when he declared martial law on Tuesday night.

The arrest list also included the leader of the main opposition Democratic Party, Lee Jae-myung, as well as three opposition lawmakers, the National Intelligence Service deputy director said.

The president tried to "use this chance to arrest them and wipe them out", said director Hong Jang-won.

The revelation came as the country's political parties held emergency meetings throughout Friday, with MPs planning to bring a vote to impeach Yoon. The motion, which is scheduled for Saturday, will pass if two-thirds of MPs vote for it.

The opposition have a majority in the 300-seat parliament but need the support of at least eight ruling party MPs to secure the 200 votes required for the impeachment motion to pass.

In the first clear sign his own party may now vote with the opposition, the leader of Yoon's ruling party called for his swift suspension on Friday, saying he posed a "great danger" to democracy if he remained in power.

Han Dong-hoon, chief of the People Power Party (PPP), had earlier in the week said his party would not support the opposition's impeachment motion.

But on Friday he announced there was "credible evidence" that Yoon had ordered the arrest of key politicians - including himself- on "anti-state charges" on Tuesday.

Han said Yoon had planned to jail arrested politicians in a detention centre in Gwacheon, a city south of Seoul.

He expressed concern that "extreme actions", such as the martial law declaration, could be repeated if Yoon remained in office.

"[These are] putting the Republic of Korea and its people at great risk.

South Koreans spent another day waiting to hear about the fate of their president on Friday, as the impeachment vote loomed.

In the afternoon, there were reports the president was heading to parliament, which his office denied. But opposition MPs lined up to block entry to the assembly, chanting "impeach, impeach".

Earlier, special forces commander Kwak Jong-kuen had assured parliament he would refuse to follow such an order if martial law was declared again, as the opposition have been suggesting it might be.

Kwak said on Tuesday night he had rejected orders to remove MPs from the assembly floor when they were gathering to vote down the martial law declaration.

"I ordered soldiers not to enter the floor... I ordered that no live ammunition be given out [and] that no harm must come to the civilians," he said.

Later in the day, he and other two other commanders were suspended for executing the martial law order before it was revoked.

Yoon's attempt to impose martial law shocked the country and unnerved South Korea's allies and financial markets.

He cited threats from "anti-state forces" and North Korea. But it soon became clear that his move had been spurred not by external threats but by his own domestic political troubles.

The order was abruptly reversed hours later after 190 MPs managed to make it into the parliament and vote it down - some of them climbing fences and breaking barricades to get into the chamber.

Opposition lawmakers are concerned that there will be another attempt to impose martial law. Some of them earlier told BBC they have been staying close to the National Assembly grounds so they could get there quickly to vote down any such declaration.

The capital, Seoul, has seen more than two days of street protests demanding Yoon's resignation, while police said he is being investigated for "insurrection".

People have also been flooding PPP lawmakers with text messages, urging them to vote for Yoon's impeachment, according to South Korean media reports.

One MP, Shin Sung-bum, received more than 4,000 such messages on Facebook, The Chosun Daily reported.

Cho Kyung-tae was the first ruling party MP to publicly voice support for Yoon's impeachment.

"The choice between standing on the side of the people by suspending the president's duties or becoming an ally of the forces that imposed martial law is a matter for politicians to judge," Cho said on Friday.

"I hope that all the politicians of the People's Power will stand on the side of the people," he added.

More than seven out of 10 South Koreans were in favour of the impeachment, a survey by local pollster Realmeter showed on Thursday.

Yoon has not been seen or spoken publicly since reversing the martial law order early on Wednesday. A survey conducted from Tuesday to Thursday this week showed his approval rating had tumbled to a record low of 13%.

Before his attempt to place the country under military rule, the president had already been beset by low popularity ratings, corruption allegations and an opposition-led legislature that reduced him to a lame-duck leader. — BBC