CAT/C/BGR/CO/4-5 in the cells, and the provision of psychosocial support care for detainees who require psychiatric supervision and treatment. The Committee invites the State party to increase the use of alternatives to imprisonment in conformity with the United Nations Standard Minimum Rules for Non-custodial Measures (Tokyo Rules) and to reduce overcrowding. 22. The Committee is concerned at the reported continued existence of underground investigative detention facilities in five locations where remand prisoners are held. It is concerned that some cells do not have windows, some have less than 1 m 2 of living space per detainee while others do not have possibilities for outdoor exercise. Furthermore, the Committee is concerned by conditions of detention in many police stations where cells do not conform to international standards of hygiene and are unsustainable for overnight use, and that in some cases detained persons spend the first 24 hours in an area with bars referred to as the “cage”, at times in full view of visitors to the police station. While noting that handcuffing people to bars and pipes has been prohibited, the Committee is concerned at reports that some detainees were handcuffed to immovable objects such as radiators and piping or to a chair for up to six hours (art. 11). The Committee recommends that: (a) The State party take urgent measures to ensure that the treatment of remand prisoners in investigative detention centres and detainees in police stations conforms to international standards. It urges the State party to build new investigative detention centres or adapt and renovate existing facilities so that all persons are detained above the ground and that they meet minimal international standards. Police detention facilities should have a sufficient number of cells suitable for overnight stay with adequate material conditions such as clean mattresses and blankets and adequate lighting, ventilation and heating; and (b) Handcuffing persons to immovable objects should be forbidden by law and in practice. Inter-prisoner violence and deaths in detention 23. The Committee is concerned that overcrowding and understaffing are conducive to inter-prisoner and violence, including sexual violence, in detention facilities, especially during the night; that of a total of 3,161 cases of violence in the period January 2007–July 2011, investigation procedures were opened only with regard to 22 cases. The Committee is also concerned about reports of increased inter-prisoner violence since 2008 and especially in 2011. It is concerned by the incidence of sexual violence, which is rarely reported, including rape, and of harassment and beatings which have on occasion resulted in suicide, as well as the large number of deaths in custody which varies between 40 and 50 annually (arts. 2, 11 and 16). The Committee recommends that the State party: (a) Enhance efforts to prevent inter-prisoner violence by addressing the factors which contribute to it such as overcrowding, lack of sufficient staff, lack of space and poor material conditions, lack of purposeful activities, availability of drugs, and feuding gangs; (b) Pay attention to protection of prisoners from inter-prisoner violence, in particular those belonging to the lesbian, gay, bisexual and transgender group, and to the psychosocial profile of the prisoners and those who engage in violence, investigate and sanction incidents; (c) Increase the number of staff, including those with training in the management of inter-prisoner violence; 9