South Korea’s most powerful businessmen were summoned by the prosecution over the weekend to answer questions about their alleged closed-door meetings with President Park Geun-hye last year.

The move comes amid deepening suspicions over their dubious ties with the nation’s troubled leader, who is at the center of an influence-peddling scandal involving her longtime friend.

A special investigation team at the Seoul Central Prosecutors’ Office said it had questioned Samsung Electronics Vice Chairman Lee Jae-yong, LG Group Chairman Koo Bon-moo and CJ Group co-Chairman Sohn Kyung-shik. SK Group Chairman Chey Tae-won and Hanjin Group Chairman Cho Yang-ho were also summoned even though they were not on the list of tycoons said to have had one-on-one meetings with Park.

On Saturday, the prosecution summoned Hyundai Motor Group Chairman Chung Mong-koo, Hanwha Group Chairman Kim Seung-youn and Kim Chang-geun, chairman of SK Supex Council, who was said to have met Park instead of Chey.

The summonses were carried out unofficially, an official at the team said. The tycoons were all summoned as witnesses, the official added.

The questioning came after the prosecution obtained a Cheong Wa Dae document on Park’s schedule, which stated that she met the seven business leaders one-on-one on July 25 last year.

The business leaders were to be asked whether the president demanded them to provide funds for the operations of two controversial foundations led by her longtime friend Choi Soon-sil. The focus of the investigation was to find out whether Park was involved with the foundations, but it can be shifted also to the businesses if their donations were made in exchange for business favors, according to legal sources.

Officials at the companies declined to comment, saying they were not told of an exact timeline of the tycoons entering the prosecutors’ office.

Hanjin Group Cho Yang-ho was also summoned despite his denial of meeting Park. He was questioned on a separate issue -- whether he was pressured to step down from the chairman post of the PyeongChang Olympics Committee by a former vice culture minister, allegedly a close associate of Choi.

The seven conglomerates made massive donations to the Mir and K-Sports foundations. Samsung Group, through a number of its affiliates, offered a combined 20.4 billion won ($17.5 million), while Hyundai Motor Group donated 12.8 billion won. SK Group gave 11.1 billion won while Hanwha offered 2.5 billion won, according to the reports.

A report by a local corporate tracker, chaebul.com, showed that the seven companies spent more on nonoperating expenses last year than in the previous year.

Nonoperating costs reported by 75 listed companies under the seven conglomerates surged 16.2 percent to 27.2 trillion won last year in contrast to a 0.3 percent increase in their operating expenses. Non-operating expenses refer to money spent on things including donations, interest payments and losses in invested assets.

In a separate probe, the prosecution summoned Posco Chairman Kwon Oh-joon on Friday evening over suspicions surrounding the alleged involvement of Choi’s associates in the company’s 2014 sale of an in-house ad agency, Poreka.

Suspicions have been growing that a former senior presidential secretary tried to intimidate a local ad company into purchasing Poreka and handing over 80 percent of its shares to a third party associated with Cha Eun-taek, a close associate of Choi. Kwon who finalized the sale of Poreka, is being questioned on whether he was aware of such a scheme. 

Samsung Electronics President Park Sang-jin, who is in charge of the tech giant’s external affairs, was also questioned for 19 hours over his involvement in suspicious donations to Choi’s daughter Chung Yoo-ra.

Reports emerged that Samsung gave 2.8 million euros ($3.04 million) to a company called Widec Sports owned by Choi and her daughter, a former member of the national equestrian team.

Samsung Electronics is the main sponsor of the Korea Equestrian Federation, while Park serves as the chairman of the organization.

Before summoning Park, the prosecution raided Samsung’s head office in southern Seoul last week.

By Cho Chung-un (christory@heraldcorp.com)