South Korean police said Wednesday that North Korea was behind three separate cyberattacks carried out earlier this year, claiming the reclusive country sent a large number of malware-tainted emails by disguising the senders.

Between January and February, North Korea sent a large number of emails to South Koreans, including local journalists, defectors and North Korea experts, said the National Police Agency (NPA), wrapping up their months-long investigation.

In late January, a link to a video clip, edited as if South Korean President Park Geun-hye was supporting the North's nuclear development, was distributed to 38,988 people.

Police said the emails, which were disguised as if they were sent from local broadcasters, seem to be part of a propaganda campaign by the North.

In the following month, more emails, pretending to be from a police officer, were sent to 48 people, including North Korean defectors and Pyongyang experts, asking for cooperation in the investigation of the fake video clip. Police said the emails contained viruses that could have infected the recipients' computers.

In mid-January, a third email pretending to be from a South Korean expert on Pyongyang was sent to 83 people, including several local reporters.

No damage has yet been reported due to this series of cyberattacks, the NPA said.

Police said checking the Internet Protocol address -- the online equivalent of a street address -- showed all the messages coming from North Korea's capital city.

"Following the recent sanctions imposed on North Korea by the U.N. Security Council, it is likely that the North will continue to distribute malware through emails," a police officer said, urging citizens and organizations to be cautious.

North Korea has a track record of waging cyberattacks on South Korea and the United States in recent years, though it has consistently denied any involvement. (Yonhap)