South Korean intelligence authorities suspect North Korea may have been behind hacking attacks on cryptocurrency exchanges in the South.

The National Intelligence Service(NIS) said Saturday that it has secured evidence showing North Korea's involvement in hacking incidents including one in June that concerned the leak of the personal information of some 30-thousand users of South Korea's largest cryptocurrency exchange "Bithumb."

The evidence has been handed over to the prosecution.

In another incident in September, virtual currencies were stolen from another exchange called "Coinis."

The NIS confirmed that the malicious code used in the hacking attacks is identical to the code used by the hacking group known as Lazarus, which is suspected of having ties with North Korea.

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