Related Rule
Belgium
Practice Relating to Rule 128. Release and Return of Persons Deprived of Their Liberty
Belgium’s Penal Code (1867), as amended in 2003, provides:
War crimes envisaged in the 1949 [Geneva] Conventions … and in the [1977 Additional Protocols I and II] … , as well as in Article 8(2)(f) of the [1998 ICC Statute], and listed below, … constitute crimes under international law and shall be punished in accordance with the provisions of the present title … :
32. unjustifiable delay in the repatriation of prisoners of war and civilians. 
Belgium, Penal Code, 1867, as amended on 5 August 2003, Chapter III, Title I bis, Article 136 quater, § 1(32).
Under Belgium’s Law concerning the Repression of Grave Breaches of the Geneva Conventions and their Additional Protocols (1993), as amended in 1999, “unjustifiable delay in the repatriation of prisoners of war or civilians” is a grave breach and, as such, a criminal offence. 
Belgium, Law concerning the Repression of Grave Breaches of the Geneva Conventions and their Additional Protocols, 1993, as amended in 1999, Article 1(3)(18).
Belgium’s Law relating to the Repression of Grave Breaches of International Humanitarian Law (1993), as amended in 2003, provides:
War crimes envisaged in the 1949 [Geneva] Conventions … and in the [1977 Additional Protocols I and II] … , as well as in Article 8(2)(f) of the [1998 ICC Statute], and listed below, … constitute crimes under international law and shall be punished in accordance with the provisions of the present title … :
18. unjustifiable delay in the repatriation of prisoners of war and civilians. 
Belgium, Law relating to the Repression of Grave Breaches of International Humanitarian Law, 1993, as amended on 23 April 2003, Article 1 ter, § 1(18).