Police block union members' entrance into the office of the Korean Construction Workers Union in Yeongdeungpo-gu, southern Seoul, during the execution of a search and seizure warrant, Friday. (Yonhap)

Police raided the office of Korea's major construction workers union on Friday, accusing them of staging an illegal protest last month, amid the Yoon Suk Yeol administration's ongoing crackdown on labor unions.

According to police, investigators from the Seoul Namdaemun Police Station were dispatched to the office of the Korean Construction Workers Union, known as the more militant of the nation's two largest labor unions, in Yeongdeungpo-gu, southern Seoul, to carry out an early morning search and seizure operation.

The police have booked the leadership of the union, including Jang Og-ki, chairman of the construction workers union affiliated with the Korean Confederation of Trade Unions, on suspicions of violating multiple laws, including the Protest Act, the Road Traffic Act and the Public Property Act.

The police stated that Jang had repeatedly failed to respond to requests to attend the police investigation meeting by May 8.

The construction union reportedly informed the police that they would be willing to meet after the funeral of Yang Hoi-dong, a union member who died after setting himself on fire in May. However, in light of the police raid on their offices, the union stated that they would reconsider attending the investigation.