Police say North Korea appears to be responsible for the hacking of the South Korean online shopping mall Interpark, which resulted in the loss of over ten million customers' account information.

The Korean National Police Agency's Cyber Bureau and a joint government investigation team announced Thursday that hackers working for North Korea's General Bureau of Reconnaissance are strongly suspected as the perpetrators based on facts confirmed so far including the Internet Protocol addresses used in the attack.

The police said that four IP addresses in three countries used in the hack were identical to those used in a previous hacking case carried out by the North before. Investigators also said that malicious codes used were also similar to past examples of North Korean hacks.

The IP address of the North's Ministry of Post and Telecommunications was used in multiple hacking attacks against South Korea that targeted government agencies and financial firms in 2009, the Joongang Daily's computer system in 2012 and the presidential office in 2013.

In the Interpark case, after obtaining the leaked data back in May, the hacker is said to have begun sending emails to the company's executives since early this month, demanding three billion won in the virtual currency bitcoins and threatening to publicize the data leak. 

Investigators believe personal records of ten-point-three million users were compromised in the latest leak including their names, online IDs, home addresses and phone numbers.