South Korea's SK Telecom said Tuesday that it confirmed the existence of a situation where hackers caused the leakage of USIM cards and other information by implanting malware at around 11 p.m. on April 19th.

SK Telecom said it is now further investigating whether sensitive information such as user names and ID numbers were leaked.

The company said it has immediately removed the malware in question and isolated the suspected hacking device, and has not yet discovered any misuse of the information.

Meanwhile, SK Telecom announced that it will offer free information protection services through its website and other channels for users who need additional security measures.