The North Korean news website Uriminzokkiri was shut down Thursday morning, allegedly by Anonymous, the BBC reported.
Twitter and Flickr accounts associated with the website were also breached, the BBC said.
The hackers have called on North Korean leader Kim Jong-un to step down from power and for a democratic government to be put in place.
In a letter posted online, Anonymous said: "To the citizens of North Korea we suggest to rise up and bring [this] oppressive government down"
"We are holding your back and your hand, while you take the journey to freedom, democracy and peace," Anonymous wrote. "You are not alone. Don't fear us, we are not terrorist, we are the good guys from the internet. AnonKorea and all the other Anons are here to set you free."
Anonymous said it had also obtained accessed 15,000 usernames and passwords from a university database.
The website for Air Koryo, a North Korean airline, was also down Thursday.
Currently, only a select few of North Korea's citizens have access to the Internet, which actually only gives them access to a few government-run websites, the BBC said.