Prosecutors on Friday raided Samsung Electronics Service as they reopened an investigation into allegations that Samsung Group sabotaged the establishment of labor unions in its affiliated companies.

The Seoul Central District Prosecutors' Office said investigators were sent to the headquarters of the after-sales service arm of Samsung Electronics in Suwon, Gyeonggi Province.

The prosecution in February secured thousands of pages of documents that contain details regarding the top conglomerate's attempts to hamper workers' efforts to set up labor unions. Samsung is notorious for its "no union" policy.

The files were obtained during a raid of two Samsung Electronics buildings as part of an investigation into suspicions that it paid retaining fees on behalf of a company allegedly owned by former President Lee Myung-bak.

The prosecution investigated Samsung's alleged anti-union maneuvers in 2013.

At that time an opposition lawmaker disclosed the group's 2012 report containing guidelines to prevent employees from organizing labor unions and to dismantle them if they form. Samsung workers and civic activists filed a complaint against Chairman Lee Kun-hee and other group officials.

But the prosecution dropped most charges and closed the case in 2015. (Yonhap)