Related Rule
Russian Federation
Practice Relating to Rule 108. Mercenaries
Section B. Status of mercenaries
The Russian Federation’s Regulations on the Application of IHL (2001) states:
When fallen into the power of the adversary, neither spies, nor mercenaries shall have the right to the prisoner-of-war status and shall be subject to punishment for their activities. However, sentences with respect to the above persons shall only be passed with previous judgment pronounced by a regularly constituted court and the accused shall be provided with the generally recognized guarantees of court defence. 
Russian Federation, Regulations on the Application of International Humanitarian Law by the Armed Forces of the Russian Federation, Ministry of Defence of the Russian Federation, Moscow, 8 August 2001, § 1.
The Russian Federation’s Criminal Code (1996) provides: “Participation of a mercenary in an armed conflict or in hostilities shall be punished by imprisonment for a term of three to seven years.” 
Russian Federation, Criminal Code, 1996, Article 359(3).
The Report on the Practice of the Russian Federation states:
As far as mercenaries are concerned, it must be said that they participate in nearly all the conflicts in the CIS countries. In connection with various political considerations, however, their legal status is made equal to the status of “volunteers”. Once Georgians brought down a plane and captured a mercenary – an officer of the Russian armed forces who fought for Abkhazia. Georgia demonstrated goodwill: it released the man and handed him over to Russia. 
Report on the Practice of the Russian Federation, 1997, Chapter 5.3.