SEOUL, South Korea: Google Inc. has helped fill the gap in one of the last remaining information black holes in the world by releasing a detailed map of North Korea that adds street names, monuments - and its notorious prison camps.

Information on streets, parks, monuments and train stops in the capital of Pyongyang showed up on Google Maps' formerly blank map of North Korea this week. Until Tuesday, the isolated communist regime was the last place on Google Maps where no data was available beyond the capital city's name.

The revision came just a few weeks after Eric Schmidt, Google's executive chairman, visited the country as part of nine-person delegation to North Korea. During the four-day personal trip that was opposed by the U.S. government, Schmidt visited computer labs at North Korea's top university and chatted with students there.

Google said there is "absolutely no connection in the timing" of the map's launch and Schmidt's North Korea visit.

Google said a community of "citizen cartographers" started building the North Korea map in 2009 based on satellite images, public information and local knowledge through a tool called Map Maker that allows collaboration on maps through crowd-sourcing. An average North Korean would not likely be able to contribute, however, since only a select few have pre-approved Internet access.

The U.S. company decided that it had enough information to make the map available to public this week.

Jayanth Mysore, Google's senior product manager, said on Google's official blog that the North Korea map is "not perfect" and asked for more contributions.

Through Google Map Maker, a service launched in 2008, users can add data to maps of places lacking accurate and detailed maps, like Pakistan and Afghanistan. Local residents can update maps of their communities with details like new bike paths that governments or other authorities can't easily track.

The map of the North Korean capital offers more details than other parts of the country, including the names of streets and the location of the square named after the country's late founder, Kim Il Sung.

Google Maps also links to photographs taken in North Korea. Many of these photos show streets and buildings of Pyongyang taken by visitors while some photos are from North-Korea focused websites, such as NKeconWatch.com.

The rest of the country remains mostly blank but some airports, highways, universities and major streets are marked.

The map also marks at least four places where North Korea's government is suspected of operating prison camps.

An Myung-chul, who heads a nonprofit organization called Free the NK Gulag in Seoul that gathers information from former North Korean prisoners, said Google Maps' information on North's prison camps are "mostly accurate" although a concentration camp near Kaechon should be farther south.

The group said it believes there were five prison camps in North Korea before one was shut down in mid-2012 based on its analysis of satellite images and testimonies from former prisoners.