Prosecutors raided the offices of Booyoung Group, a major construction and real estate business group, on Tuesday as part of a probe into a string of suspected irregularities involving its chairman.

Investigators from the Seoul Central District Prosecutors' Office raided Booyoung Housing headquarters and other properties in central Seoul to confiscate evidence, including accounting books and computer hard drives, the office said.

The prosecutors are looking into allegations that Booyoung Housing chairman and chief executive Lee Joong-keun is involved in a series of crimes, from tax-dodging to managing a slush fund.

With some 22 trillion won ($26.2 billion) in assets, Booyoung is the nation's 16th-largest conglomerate which focuses on apartment construction and leisure facilities.

The National Tax Service filed a complaint with the prosecution in April last year, after a tax probe into Booyoung and the chief.

The Fair Trade Commission, the state anti-trust watchdog, also requested a prosecution investigation into suspicions that Lee avoided regulations by falsifinhg ownership disclosure for companies run by his relatives.

Lee is also seen implicated in a massive corruption scandal that brought down former President Park Geun-hye early last year. Lee allegedly asked Park's longtime friend Choi Soon-sil to use her influence to have the government tax agency close its case against him and his company, in return for a donation to a foundation allegedly controlled by Choi. Lee did not make the donation because Choi refused his proposal.

Prosecutors are also looking into suspicions that he secretly transferred some 270 billion won of slush fund to an account in Cambodia.

Prosecutors have banned Lee from leaving the country and are expected to summon him after they examine the seized evidence. (Yonhap)