In Denmark, communists had long been surveilled and perceived as a threat to national security by the political establishment and on 22 June 1941, around 300 Danish members of the Communist Party of Denmark (DKP) were arrested by the Danish police. In Copenhagen they were detained at Vestre Prison without charge and on the 20 August, 107 of the arrested men were deported from Vestre Prison to the Horserød camp, among them member of parliament Martin Nielsen.