The marks attained by the top scorer on South Korea’s national exam for aspiring tax accountants this year seemed too good to be true and on Sunday, sceptics were proven right when he confessed to using generative AI to cheat.

The scandal follows months of speculation after he scored near-perfect marks on hundreds of questions over two exams taken in April and July. It has also raised the stakes for organisers of South Korea’s high-stakes annual college entrance exam this Thursday.

“I cheated using electronic devices and generative AI. My passing the exam with the top score was not the result of fair effort,” he said, identifying himself by the surname Han, as he apologised on the YouTube channel ‘Attorney Lee Don-ho’.

Han said he cheated by taking photos of the exam questions with a microcamera, sending them to an AI tool and checking the answers on a smartphone.

Speaking on camera wearing a face mask, Han added that he had submitted a written confession to Seoul police.

A Reuters call to the Seoul Jungbu police station went unanswered on Sunday.

The scandal has rattled a country where standardised tests largely dictate social mobility and career trajectories, coming just four days ahead of Thursday’s annual national college entrance exam.

“The presidential office views the matter very seriously, and because the college entrance exam is next week, we have been working hard to prepare countermeasures,” a senior presidential office official told reporters on Sunday.

The official said that reports of potential cheating in the certified public accountant exam were concerning, adding that the presidential chief of staff for policy would convene an emergency meeting later in the afternoon to address the issue.

Prime Minister Han Seok-sook acknowledged on Friday public concerns over AI-assisted cheating ahead of the national college entrance exam, a high-pressure event that many South Korean students have spent much of their lives preparing for.

The government “will prepare thoroughly in advance and closely oversee the process until the very end to ensure the college entrance exam is conducted fairly and stably,” a statement from her office said.