Police on Thursday raided some offices of the construction unions affiliated with the country's two biggest umbrella labor organizations as part of an investigation into alleged wrongdoing at construction sites.

The Seoul Metropolitan Police Agency sent investigators to five offices belonging to the construction union of the Korean Confederation of Trade Union and three construction union offices of the Federation of Korean Trade Unions to seize evidence, officials said.

Eight houses belonging to officials of the construction unions were also searched by the police.

Police reportedly opened an investigation on suspicions that officials at the unions coerced employers to hire certain workers or asked for financial rewards in return for providing job opportunities. (Yonhap)