The Supreme Court on Tuesday unveiled 98 documents related to allegations that its former chief justice used trials as leverage to gain presidential approval for organizational changes.

An internal probe by the National Court Administration under the top court has found the NCA wrote about 410 documents in March 2015 on how to take advantage of high-profile cases so as to persuade senior presidential aides to support then-Chief Yang Sung-tae's plan to establish a court of appeals.

The agency's officials are alleged to have communicated frequently with then-President Park Geun-hye's aides and influential politicians over cases, such as those involving an opposition lawmaker, a former spy chief and a left-wing teachers' union.

Justice Ahn Chul-sang, head of the NCA, said earlier the agency would release the files without disclosing the names of the persons mentioned.

The released documents showed Yang's top court had discussed which district court should deal with the trial on the Sewol ferry sinking that took more than 300 lives in 2014. Park government's mishandling of the disaster later became one of the triggers that led to moves toward her impeachment.