Databases loaded with names, identification numbers and addresses were accessed by unauthorized and unknown parties. More than 16,000 US Army personnel stationed in South Korea, plus data on local employees and job applicants, appears to have been compromised.

Specific details of how the 28 May raid was launched were not disclosed. Banking details and classified data was not compromised.

US Army Commander Curtis M Scaparrotti said: "United States Forces Korea (USFK) was made aware of a potential theft of personal information from the Korean National Recruitment System maintained by the US Department of the Army."

"We deeply regret and apologize for any inconvenience and concern this matter may cause you. USFK takes this compromise very seriously and is reviewing policies and practices with a view of determining what must be charged to preclude a similar occurrence in the future."

The affected machine was pulled from its network and switched to a different system to handle employment applications.