Test takers are preparing to file a collective suit to invalidate a leaked Yonsei University entrance exam and seek a court injunction to suspend the test result if the school refuses a retest, citing unfairness and defrauding of early-admission candidates.

More than 100 test-takers and parents have expressed their intention to take legal action over the irregularities in the exam as of Thursday at around 3 p.m. and plan to hire a lawyer for the case, according to local media reports on Friday.

The decision comes after questions for the natural science track of Yonsei University's early admissions held Saturday were leaked an hour before the exam after the proctor distributed the paper before the scheduled time. The exam papers were recalled after 15 minutes, but some students posted online for prospective test-takers. Some 9,000 candidates reportedly took the test.

In addition, reports Friday added that a test taker who had received the exam paper in advance shared three test questions with another peer at a different location via direct messenger on Instagram.

After the incident sparked public uproar, Yonsei University -- one of the country's most prestigious colleges -- filed a complaint Tuesday with Seoul Seodamun Police Station against six people on charges of obstruction of business. Two identified applicants were from the humanities and natural sciences tracks and four others remain unidentified. Officials have assigned the case to the Seoul Metropolitan Police Agency's Public Crime Investigation Unit.

Separately, the college said it would launch its own investigation committee to look into the case, including whether the proctors had neglected their duties during the exam administration.

Yonsei, however, said the photos of the entrance exam were taken and uploaded after the exam ended, adding that it is not considering arranging a retest despite students' and parents' demands. In a statement released earlier this week, the university explained that the exam supervisors had "instructed students to turn off their phones" and "store them in their bags."

Yonsei University declined to comment further on the matter, adding that a police investigation regarding the case is ongoing.

Amid the controversy, observers and legal experts expressed skepticism over the court's approval of an injunction and a successful lawsuit as students, not the school, leaked the test questions.