The ACT entrance exam for students in South Korea and Hong Kong who are hoping to study at US colleges following evidence of a leak.

The cancellation marked the first time the high-stakes exam had been scrapped for an entire country.

ACT Administrators made the decision only hours before the 5,500 students were due to take the exam across 56 different centres. The ACT entrance exam is one of two exams available to international and domestic students hoping to study at a US college. “ACT has just received credible evidence that test materials intended for administration in these regions have been compromised,” it said in a statement.

Whilst the students will receive refunds of their registration fees, The Guardian reports that ACT spokesman Ed Colby has said that it was “not feasible” to reschedule the exam and that the ACT will not be administered again until September. “It impacts innocent students who had no involvement in any kind of wrong activities,” he added.

This outbreak of cheating by east Asian students is not the first of its kind. In May 2013, the College Board of South Korea was forced to cancel its SAT college-entrance exam tests in light of evidence that exam materials had been leaked. Tutors and owners of the test companies are currently on trail in Seoul. Additionally, exploitation of the College Board’s practice of recycling SAT tests by feeding clients test questions in advance has been discovered in China.