A/HRC/40/59/Add.2 adjudicating authorities, for periods of up to five years. Based on the information provided to the Special Rapporteur, an average of 60 per cent of persons deprived of their liberty in prisons and police stations are in pretrial detention. During his visit to Unit 23 of Florencio Varela prison complex, the Special Rapporteur was alarmed to learn that no less than 80 per cent of the prison population was in pretrial detention. 32. According to national Act No. 25430, pretrial detention should not exceed two years. An exceptional extension by an additional 12 months, up to a total of three years, is possible only in complex cases, such as multiple charge cases. After the expiry of two years, each additional day in pretrial detention counts as two days spent serving a prison sentence. At both the provincial and the federal levels, however, the Special Rapporteur found that this provision is not effectively implemented in practice, but he received consistent reports of the excessive use of pretrial detention and serious deficiencies in the process of expediting criminal proceedings. 33. Moreover, while the physical separation of pretrial detainees and convicted prisoners is required by law, several of the facilities did not have sufficient space to ensure this separation. As a result, pretrial detainees were held under the same regime as convicts. He shares the assessment of the Working Group on Arbitrary Detention that such a transformation of the nature of pretrial detention into a de facto punishment without conviction is in violation of article 10 (2) (a) of the International Covenant on Civil and Political Rights (A/HRC/39/45/Add.1, para. 33). In the view of the Special Rapporteur, the instances of excessively prolonged pretrial detention observed during his visit may well amount to cruel, inhuman or degrading treatment in violation of international law. VI. Conditions of detention A. Overcrowding 34. Between 1996 and 2016, the population deprived of liberty in prisons nationwide tripled, from 25,163 to 76,261 persons. This increase is even greater when those detained in police stations are taken into account. 35. The official capacity of detention places appears to be calculated on the basis of available beds rather than available space per inmate, which results in available surface areas as small as 1 m² or less per inmate, clearly falling short of the universally recommended minimum specifications of 3.4 m2 per inmate in shared accommodation and 5.4 m2 in single cells.3 36. While the sharp increase in incarceration rates has led to significant overcrowding and deterioration of conditions of detention throughout Argentina, some provinces are particularly affected. The Special Rapporteur notes with concern that the system of adult criminal confinement in the Province of Buenos Aires exceeds 120 per cent of its occupancy capacity. In 2017, the total number of inmates in prisons and police stations reached a historical record of 42,352 detainees, with very serious repercussions on the living conditions of the detainees. 37. Overcrowding is also a concern at the federal level, although to a lesser extent. According to the Office of the Ombudsman for the Prison System, the population of the federal prison system increased by 18.5 per cent (1,853 people) between 2014 and 2017 and now exceeds 100 per cent of capacity. The Federal Prison Service reported that, as of March 2018, it was accommodating 12,034 people in federal prisons, with a shortage of 457 places, thus experiencing moderate overcrowding as compared to the rest of the country. 3 8 International Committee of the Red Cross, Water, Sanitation, Hygiene and Habitat in Prisons: Supplementary Guidance (Geneva, 2013), p. 33.