KT Corporation's recent service outage was caused by the omission of a single word command entry, a mistake made by an employee, and the absence of an internal safety device to prevent the error from wreaking nationwide havoc .

The Ministry of Science and ICT has been looking into the 90-minute blackout at the state-backed telecom giant on October 25 with a team of network specialists and announced its findings on Friday.

During a router replacement work at a KT branch office in Busan, an engineer did not input the command word "exit" at the very end. It took just 30 seconds for that blunder to disrupt services nationwide.

Other managerial issues such as a disregard for proper safety protocols exacerbated the incident, with the operation taking place during busy daytime without the presence of an overseeing officer.

The ministry confirmed that a distributed denial-of-service(DDoS) attack, initially thought to have caused the crash, did not take place.

The ministry and telecommunication service providers will formulate enhanced measures to boost network stability including introducing an advance simulation system to anticipate potential crashes.