The former president is also suspected of colluding with Choi and her aide to force dozens of companies from 18 business groups, including the three conglomerates, to pay a total of 77.4 billion won in "donations" to the Mir and K-Sports foundations, allegedly controlled by Choi.

Lee Jae-yong, de facto leader of the country's largest business group Samsung, is standing trial for allegedly providing or pledging 43.3 billion won to Choi and in effect, to Park, in return for helping him secure group control through a merger of two key units. Of the total, 20.4 billion won went to the two foundations.

Shin Dong-bin, the chairman of the country's fifth-largest business group Lotte, was also indicted for allegedly giving 7 billion won of donations to K-Sports, though the money was returned just before the retail giant was investigated over separate corporate crime allegations.

The third-largest SK Group was asked to provide 8.9 billion won to the sports foundation but rejected the demand.

Prosecutors suspect that Park promised favors regarding the two conglomerates' bids to operate duty-free shops and other pending issues in return for the money. 

Park is also accused of creating a blacklist of cultural figures deemed critical of the government to deny them state support from 2013 to 2016.
 
Prosecutors said Park allegedly sacked three senior officials at the country's culture ministry for being reluctant to execute the blacklist.

She was charged with attempted coercion for pressuring the resignation of food and entertainment giant CJ Group's Vice Chairwoman Lee Mi-kyung for TV shows and movies critical of her administration.

In other cases of abuse of power and coercion, Park is suspected of abusing her authority to promote a bank official close to Choi and pressuring local firms to sign business contracts with Choi's companies. 

South Korea's top automaker Hyundai Motor signed a 1.1 billion-won supply contract with a firm belonging to one of Choi's associates between 2015 and 2016, and a 7.1 billion-won deal with an ad agency held by Choi last year. 

Leading steelmaker Posco was forced to create a fencing team to be placed under the control of one of Choi's companies in March 2016, prosecutors said. 

Telecom giant KT was pressured to hire figures close to Choi as the company's executives and to sign a 6.8 billion-won deal with Choi's advertising company, they said.

Park was also charged with leaking 47 documents, including government secrets, to Choi from January 2013 to April 2016, through her longtime aide Jeong Ho-seong. 

During the two preparatory sessions held at the court, Park's lawyers denied all the corruption charges leveled against her. She did not appear at the two sessions as her attendance was not mandatory.

Unlike preliminary sessions, suspects are required to attend formal hearings. 

Park is the country's third former president to stand trial over corruption allegations, after Chun Doo-hwan and Roh Tae-woo, who were convicted in 1996-97. (Yonhap)