Personal details of tens of thousands of U.S. troops have been leaked to websites, South Korean online security firm said on Wednesday (June 26), a day after cyber attacks disabled access to government and news sites.

South Korean online security firm Red Alert said that personal details of more than two million South Korean ruling party workers and 40,000 U.S. troops, including those stationed in South Korea, have been released on unspecified websites.

The hacking attacks on Tuesday (June 25), the anniversary of the start of the Korean War in 1950, brought down the main websites of South Korea's presidential office and some local newspapers, prompting cyber security officials to raise the alert.

The websites of the presidential Blue House and the Prime Minister's office were down for more than six hours.

An official at the Communications Ministry said authorities were probing the nature of the attacks and declined to comment on the reports of leaked information about U.S. troops.

North Korea has been blamed for previous cyber attacks on South Korean banks and government networks, although it denies responsibility and has said it has also been a victim.

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