Flags flutter in the wind outside the prosecution service building on May 1. (Yonhap)

Prosecutors raided Doosan Engineering & Construction Co. and 20 other institutions Friday in connection with allegations of opposition leader Lee Jae-myung's third-party bribery surrounding a corporate donation to a football club years ago.

The case centers on the allegations that the city government of Seongnam, just south of Seoul, had attracted hefty donations from Doosan Engineering and other entities to a municipal football club in return for administrative favors in the mid-2010s, when the leader of the main opposition Democratic Party was serving as its mayor.

The raid came three days after police transferred the case to the prosecution with an opinion of indictment for Lee and others. Police reportedly concluded a third-party bribery charge can be applied to Lee in connection with donations totaling 5.5 billion won (US$4 million) made between 2014-16 by Doosan Engineering to Seongnam FC, then headed by Lee.

The Seongnam branch of the Suwon District Prosecutors Office sent prosecutors and investigators to about 20 locations, including Doosan Engineering, Seongnam FC and Seongnam City Hall, in the morning to search and seize documents related to the case.

Lee is suspected of changing the city's usage purpose for a 9,900-square-meter section of land owned by Doosan in the city's Bundang district from a hospital to commerce in return for the company's donation provided in the name of advertising expenses. Thanks to the zoning change, Doosan is said to have made huge profits, as the value of its Bundang property reportedly skyrocketed from 7 billion won to about 1 trillion won.

Lee was indicted by another prosecution office last week over allegations that he violated the election law by making false statements related to two land development projects in Seongnam during his presidential campaign last year. (Yonhap)