An e-mail account of a presidential official was found to have been hacked, presumably by North Korea, shortly before President Yoon Suk Yeol's state visit to Britain and trip to France last November.

In a statement to the media on Wednesday, the top office said it became aware of the hack shortly before the president's trip and took necessary measures, quickly adding that the office's security system was not hacked.

The official in question had used both the top office's e-mail account and their personal e-mail account when preparing for the presidential trip. The hacked e-mail account was found to be the official's personal one.

The top office said the latest incident was a security regulation violation that resulted from the staffer's careless act of using their personal e-mail account for work.

While a senior official of the presidential office said North Korea is presumed to be behind the hacking incident, some media reports said part of the leaked information included data on the president's itinerary for his state visit to Britain and his messages.