KT, South Korea's No. 2 mobile carrier, has reported signs of multiple external attacks on its servers.

KT said in a statement Friday that it had submitted the report to the Korea Internet and Security Agency just before midnight on the previous day.

KT said following the large-scale data breach of SK Telecom in April, the carrier had commissioned an external cybersecurity firm to conduct a companywide investigation of its servers.

KT said that the four-month investigation had identified evidence of four possible server breaches along with two other suspected cases.

KT plans to quickly identify the compromised servers through the government investigation and disclose additional details of the digital attacks.