Hackers have stolen the personal details of roughly 35 million South Korean Internet users in an attack on the company behind two of country’s largest social networking sites.

Social security information, emails, passwords, phone numbers and names were stolen from SK Communications, which operates the Nate and Cyworld websites, the Korea Communications Commission said in a statement yesterday.

In a statement to the Korea Herald newspaper, SK Communications confirmed the data breach, and said that it had been originated from machines with Chinese IP addresses.

"The company has confirmed that a leak of customers’ information has taken place due to hacking on July 26," the paper reported. "The specific scale of the hacking is still being investigated, but it is estimated that some of the personal information of 35 million Nate and Cyworld members has been leaked."

The Cyber Terror Response Center, a police division dealing with crimes in cyberspace, is expected to identify who committed the hacking, according to the Korean Herald.