South Korean prosecutors said Thursday they will question the heads of seven local conglomerates over allegations that President Park Geun-hye had pressured them to make donations to two nonprofit organizations, possibly in exchange for favors.

Investigators have arrested Choi Soon-sil, the president’s close confidante accused of pulling strings behind the scenes, Choi’s associates and former presidential secretaries on suspicions they coerced 53 companies to raise some 77.4 billion won ($67.4 million) for the Mir Foundation and K-Sports Foundation. The prosecution suspects the money may have been illegally channeled to Choi.

“We are investigating just what was discussed between (Park and company heads). ... Summoning them for questioning is not out of the question,” said an official from the Seoul Central District Prosecutors’ Office.

Prosecutors also raided the home of a former presidential aide for civil affairs, Woo Byung-woo, who is suspected of condoning Choi’s unlawful actions. Potential evidence acquired in the search included cellphones belonging to Woo and his wife.

Woo has been banned from leaving the country and faces a series of suspicions, including embezzlement and abuse of power.

Questions were raised over whether Woo was involved in leaking information related to a corruption probe on Lotte Group. Lotte donated 7 billion won to the foundations, but has since received back the funds.

Woo is also suspected of overlooking wrongdoings by former TV commercial director and Choi’s aide Cha Eun-taek, which include interfering in the president’s personnel decisions.

Investigators later in the day requested an arrest warrant for Cha, who is suspected of using his relationship with Choi to get state-backed projects and attempting to unlawfully acquire advertisement company Poreka through coercion.

The prosecution is slated to summon Posco CEO Kwon Oh-joon on Friday for questioning on suspicion his company cut its orders for Poreka after the chief executive of the company refused to comply with the threats and give up the company.

Choi, a 60-year-old civilian, is suspected of meddling in state affairs and pocketing public funds. She and An Chong-bum, a former senior presidential secretary, are suspected of playing the key role in raising funds for the foundations.

But prosecutors are conducting an investigation to see if Park herself was involved in the process, particularly after it was revealed she held a closed-door meeting with individuals heading seven of the biggest corporations in South Korea.

The individuals included Samsung Electronics Vice Chairman Lee Jay-yong, Hyundai Motor Group chief Chung Mong-koo and LG Group Chairman Koo Bon-moo.

Officials from Samsung, Hyundai Motor, LG, SK, CJ, Hanhwa and Hanjin have already been summoned for questioning on the allegation.

Reports have indicated that the companies related to the Mir and K-Sports foundations made donations in exchange for favors, such as being exempt from tax audits.

Local Channel-A reported Wednesday that one of Choi’s aides had approached the son of Hwanhwa Group Chairman Kim Seung-yeon, who was then on trial for unlawful financial aid to one of the company’s subsidiaries. The aide reportedly told Kim it was possible for his father to receive a presidential pardon through Choi.

An official of Hanhwa also told the media the company relinquished its sponsorship of the Korea Equestrian Federation because it was unable to comply with the demands of Choi concerning her daughter Chung Yoo-ra, a professional dressage rider.

“Considering that most of the companies made sizeable donations without complaints, and that the president pursued policies favorable to corporations afterward, we cannot but help wonder if the corporation heads had no choice when they provided the funding,” said Lawyers for a Democratic Society, also known as Minbyun, in a statement.

It added that after the scandal broke out, high-ranking officials from Samsung Electronics -- the company that made the biggest contributions -- secretly left for Germany, where Choi and her daughter were residing at the time.

By Yoon Min-sik (minsikyoon@heraldcorp.com)