South Korean investigators have again sought to question impeached President Yoon Suk Yeol over his declaration of martial law.

On Friday, they summoned him for questioning on Christmas Day despite his repeated refusal to cooperate.

The Corruption Investigation Office for High-Ranking Officials, which is leading a joint investigation with police and military authorities into the ill-conceived power grab on December 3 that lasted only a few hours, said it plans to question Mr Yoon on charges of abuse of authority and orchestrating a rebellion.

Mr Yoon, whose presidential powers have been suspended since the opposition-controlled National Assembly impeached him on December 14, has dodged several requests by the joint investigation team and public prosecutors while also blocking searches of his office.

Members of civic groups shout slogans during a rally demanding South Korea’s impeached President Yoon Suk Yeol to resign (AP/Lee Jin-man)

It is not clear what investigators can do if Mr Yoon continues to reject their demands. Under the country’s laws, locations potentially linked to military secrets cannot be seized or searched without the consent of the person in charge, and it is unlikely Mr Yoon will voluntarily leave his residence if he faces being compelled to appear.

The president is focusing on defending himself at the Constitutional Court, which following his impeachment will decide whether to remove him from office or reinstate his powers.

Authorities have already arrested Mr Yoon’s defence minister, police chief and several other military commanders involved in the attempt to enforce the martial law decree, which harkened back to the days of authoritarian leaders the country has not seen since the 1980s.

Mr Yoon and his military leadership have been accused of attempting to block parliament from voting to end martial law by sending hundreds of heavily armed troops to encircle the National Assembly. The president says the troops were there to maintain order.

Kwak Jong-keun, the now arrested commander of the Army Special Warfare Command, testified in parliament that Mr Yoon had asked for his troops to “quickly destroy the door and drag out the lawmakers who are inside” the Assembly’s main chamber where the vote occurred. Mr Kwak said he did not carry out Yoon’s orders.

South Korea’s main opposition Democratic Party leader Lee Jae-myung (AP/Ahn Young-joon)

Mr Yoon has also been accused of ordering defence intelligence officials to detain key politicians, including opposition leader Lee Jae-myung, National Assembly speaker Woo Won Shik and the ex-leader of his own conservative party, Han Dong-hun, according to a high-ranking intelligence official and Mr Han himself, a reformist who supported investigations into corruption allegations against first lady Kim Keon Hee.

Seok Dong-hyeon, a lawyer and spokesperson for Mr Yoon’s emerging legal team, defended the president’s actions, echoing Mr Yoon’s assertion that he did not commit rebellion but saw martial law as an emergency measure to counter the main opposition Democratic Party, which used its parliamentary majority to obstruct his agenda.

Mr Seok insisted that Mr Yoon had no intentions to paralyze the parliament’s functions, despite the troop deployment to the National Assembly, and claimed he never ordered politicians to be detained.

When asked whether Mr Yoon would continue to ignore authorities’ requests to question him and search his office, Mr Seok declined to give a specific answer, saying that these matters would be handled by the president’s legal team, which he said has been nearly assembled.

Some experts say any attempt to compel Mr Yoon to appear for questioning would ultimately require the consent of the country’s acting leader, Prime Minister Han Duck-soo, who is locked in a standoff with the opposition Democratic Party after he vetoed several controversial agricultural bills backed by the party.