South Korean investigators have raided the offices of three of the country's biggest corporations as part of the probe into alleged influence-peddling surrounding embattled President Park Geun-hye.

On Thursday, prosecutors showed up at the offices of Lotte Group, SK Group, and several government agencies.  A day earlier, they carried out similar searches at offices of Samsung Group, South Korea's largest family-run conglomerate and the parent of global smartphone leader Samsung Electronics.

Prosecutors suspect the businesses of funneling money to organizations controlled or owned by Choi Soon-sil to win government favors in relation to duty free licenses.  Ms. Choi is a close friend of President Park.  Last weekend, prosecutors indicted Ms. Choi - a close friend of President Park - last weekend and a former aide of Park on charges of pressuring companies to contribute funds to her foundations.

The South Korean Finance Ministry and a Lotto Group spokesman confirmed the raids, the rest stayed silent.