"Raids were also being conducted at the offices of the Seoul Metropolitan Police and the National Assembly Police Guards," the police said in a statement.
Yoon imposed martial law on the night of Dec. 3, but 190 lawmakers rushed to parliament and passed a motion to lift it, forcing him to rescind the decision.
It triggered a political crisis, with calls for President Yoon, the first sitting president to face treason charges and a travel ban, to resign.
The 63-year-old president faces charges of treason and insurrection and has been banned from overseas travel. He can face arrest as well.
If the situation "warrants, we will attempt an immediate arrest" of Yoon, Oh Dong-woon, head of the Corruption Investigation Office for High-ranking Officials, told lawmakers.
A sitting South Korean president is immune from prosecution except in cases of insurrection.
AzVision.az
More about: SouthKorea
