Samsung heir Lee Jae-yong arrives to be questioned in the corruption scandal of President Park Geun-hye. Photo: AFP, Pool

Samsung heir Lee Jae-yong was grilled by South Korean prosecutors Thursday after becoming a criminal suspect in the corruption scandal engulfing impeached President Park Geun-hye.

Lee, chairman of Samsung Electronics and the son of the Samsung Group chairman Lee Kun-hee, was to be questioned in connection to allegations of bribery, prosecutors said Wednesday.

Park’s confidante Choi Soon-sil is accused of using her ties to Park to coerce top firms into donating tens of millions of dollars to two non-profit foundations that Choi then used as her personal ATMs.

Samsung was the biggest contributor to the foundations. It is also accused of separately giving millions of euros to Choi to bankroll her daughter’s equestrian training in Germany in a bid to curry favor.

Prosecutors have for months questioned Lee and other senior Samsung officials, who reportedly argued that they sought no favors and thus the payments were not a bribe.

Prosecutors are investigating whether Samsung bribed Choi in order to win state approval for a controversial merger which it sought in 2015.

The merger of two Samsung group units — Cheil Industries and Samsung C&T — was seen as a crucial step towards ensuring a smooth third-generation power transfer to Lee Jae-yong.

Critics said it wilfully undervalued Samsung C&T’s stocks. But the National Pension Service — a major Samsung shareholder — voted in favour of the deal and it eventually went through.