This form of forced labor was handled by the Chief Directorate for Prisoners of War and Internees Affairs (Главное управление по делам военнопленных и интернированных, ГУПВИ, transliterated as GUPVI) of the NKVD, established in 1939 (initially as the "Directorate for Prisoners' Affairs", управление по делам военнопленных) according to the NKVD Order no.
The first POW camps were formed in the European part of the USSR.
By the end of World War II, the Soviet Union amassed a huge number of German and Japanese and other Axis Powers POW, estimated over 5 million[1](of which estimated 15% died in captivity[2]), as well as interned German civilians used as part of the reparations.
[1] Many POWs were used for the reconstruction of cities damaged by the Wehrmacht during World War II.
In 2000 a collection of Soviet archived documents related to POWs in the Soviet union was published in Russia, with an introduction, map of POW camps, and comments.