Two senior Samsung executives have been questioned as part of the corruption probe surrounding South Korea's impeached president, Park Geun-hye.
The firm is accused of giving large donations to non-profit foundations operated by Choi Soon-sil, a close confidante of Ms Park.
The donations were allegedly given in exchange for political support of a controversial merger.
Ms Choi has been charged with coercion and attempted fraud.
According to South Korea's Yonhap news agency, Choi Gee-sung, a Samsung vice chairman, and Chang Choong-ki, a president at the group, were being interviewed on Monday by special prosecutors about the corruption allegations.
It was reported the pair were being treated as witnesses, rather than being suspected of any wrongdoing.
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The claims circle around a merger between the electronics giant's construction arm, Samsung C&T, and an affiliate firm, Cheil Industries.
The deal went through despite significant opposition from shareholders, who said it would hurt minority shareholders while benefiting the family of Samsung's group owner Lee Kun-hee.
South Korea's National Pension Service (NPS), which owns stakes in both companies, sealed the deal by voting in favour of it and the head of the NPS has since been arrested.
But prosecutors also allege that Samsung gave €2.8m euros ($3.1m; £2.5m) to a company co-owned by Ms Choi and her daughter, in return for Ms Park's support for the deal.