South Korean prosecutors raided the offices of Samsung Group on Wednesday, a prosecution official said, after media reports of alleged links with a confidante of President Park Geun-hye who has been indicted in an influence-peddling scandal.

Prosecutors also raided South Korea's largest pension fund, the National Pension Service (NPS), an NPS spokeswoman said. The Yonhap news agency reported that investigators were probing NPS's decision to approve the $8 billion merger of Samsung C&T Corp and Cheil Industries last year. The raids signalled that prosecutors are expanding their investigation into allegations of influence-peddling in the corruption scandal that has rocked Park's presidency over the relationship between the government and big businesses. NPS, the world's third-largest pension fund, has come under scrutiny by the media and civic groups over its approval as a major shareholder of the merger between two affiliates of Samsung Group, South Korea's largest family-run conglomerate.

Samsung signage on display at the Mobile World Congress in Barcelona, Spain on Feb. 22, 2016. Brad Quick | CNBC

Its backing was seen as crucial to the success of the merger and some South Korean media reports said its approval came under mysterious circumstances. A Samsung Group spokeswoman confirmed prosecution officials had visited the group's headquarters but she could not provide further details. The NPS spokeswoman declined to give further details. Prosecutors raided four locations - the NPS headquarters, NPS Investment Management office headquarters, Samsung Group offices and the office of a former NPS investment management official - said a prosecution official who was not authorised to speak to the media and declined to be identified. Park and her confidante, Choi Soon-sil, are under investigation for allegedly improperly pressuring major conglomerates, including the Samsung Group, to raise funds for foundations that backed Park's policy of promoting the cultural and sports communities.

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