A/67/44 and prisons, insufficient staff levels, including medical professionals, and lack of basic supplies (arts. 2, 11 and 16). The State party should adopt urgent and effective measures to ensure that detention conditions in police stations, prisons and other detention facilities are in conformity with the United Nations Standard Minimum Rules for the Treatment of Prisoners (Beijing Rules). In particular, the State party should: (a) Alleviate the overcrowding in prisons, including through the wider use of non-custodial measures as an alternative to prison sentences; (b) Take immediate and effective measures to improve the material and sanitary conditions in both police stations and prisons, ensure the provision of basic supplies, and appoint a sufficient number of trained staff, including medical professionals. Prolonged periods of pretrial detention, juveniles (15) While noting some recent legislative initiatives, the Committee is concerned at the long periods of pretrial detention, including in the case of juveniles, due to shortcomings and considerable delays in the judicial system. The Committee is also concerned at the limited use of non-custodial measures for juvenile detainees. It is further concerned that separation between pretrial and convicted detainees as well as juveniles and adults is not always guaranteed (arts. 2 and 11). The State party should take effective measures to considerably reduce the length of pretrial detention. Such measures include reform of the judicial system to ensure that pretrial detainees receive a fair and speedy trial, as well as application of alternative pretrial restrictions. In the case of juveniles, detention should only be used in exceptional circumstances or as a measure of last resort, on grounds specifically prescribed by law, and then only for the shortest possible time. Furthermore, the State party should ensure strict separation between pretrial and convicted detainees and between juveniles and adults in all detention facilities. Body cavity searches (16) The Committee expresses its concern at the continued use of invasive body cavity searches, especially internal, in detention facilities (arts. 11 and 16). The State party should exercise strict supervision of body search procedures, especially internal searches, by ensuring that these are performed in a way that is the least intrusive and most respectful of the integrity of the individual, and in all cases in compliance with the terms of the Convention. The Committee also recommends that the State party consider alternatives such as electronic detection methods. Systematic monitoring of detention facilities, national preventive mechanism (17) While noting that a number of organizations have a mandate to visit places of detention and the policy referred to by the delegation to grant NGOs and other bodies access to prisons, the Committee is concerned that such visits currently take place on an ad hoc basis due to the absence of an independent organization in charge of systematic monitoring of all detention facilities. The Committee notes, however that the State party signed the Optional Protocol to the Convention on 3 March 2011 and that a recent draft law designates the Greek Ombudsman as the national preventative mechanism (NPM) (arts. 2 and 11). The State party should ensure that a system of systematic monitoring of all detention facilities, including facilities for migrants and asylum seekers, be set up. In this respect, the Committee recommends that the State party ratify the Optional Protocol 144 GE.12-44492