The Ministry of Posts and Telecommunications announcement was posted this week at the country's main mobile service provider, Koryolink, and other places serving Internet users.
It said "anti-republic false propaganda websites, sex and adult websites" are blocked, along with YouTube, Facebook, Twitter, Voice of America and South Korean media sites. Such sites had been informally blocked for months, and they could not be accessed Friday in a Web search from Pyongyang.
Very few North Koreans have Internet access. Typically they can only see a sealed-off, government-sanctioned intranet. But foreigners in the country had previously been able to surf the Web freely.
Related story
South Korea says North Korea’s latest launches were missiles
