The brutal regime is said to be executing people for crimes including copper theft, prostitution and distributing media from neighbouring South Korea.
The Transitional Justice Working Group (TJWG), who made the claims, said they wanted to highlight human rights abuses in the country.
They interviewed some 375 North Korean defectors over a period of two years before making their findings public.
The group said: “The maps and the accompanying testimonies create a picture of the scale of the abuses that have taken place over decades.”
It added that the those sentenced to death are usually shot in public areas, altho one interviewee told the group that other are simply beaten to death as their crimes “were considered no worth wasting bullets on”.
North Korea, led by Kim Jong Un, has rejected any charges of human rights abuses, insisting citizens enjoy protection under the constitution.
However, a United Nations report in 2014 claimed the country had built large prison camps which carried out torture, abuse and executions that was on a scale comparable to the Nazis in World War Two.
Top pic: Rex