- 23 47. The CPT considers that the electronic recording of police interrogations represents another important safeguard for detainees, as well as offering advantages for the police. However, its delegation was informed that such a system is not currently used in Greece. The CPT recommends that the Greek authorities explore the possibility of introducing an electronic recording system for police interrogations. The system should offer all appropriate guarantees (for example, the detainee's consent; the use of two tapes, one of which would be sealed in the presence of the detainee and the other used as a working copy). 48. As already indicated (cf. paragraph 14), a detainee may remain on police premises for several days while awaiting a judicial decision on his release or remand in custody. However, all police officers spoken to stated that once the detainee had been brought before the public prosecutor, their power to question him ceased (further questioning being carried out by the public prosecutor or the competent judge). The CPT would like to receive confirmation of this position and to be informed whether the rule against further questioning by the police covers questions about other matters falling outside the scope of the charges already laid against the detainee. g. supervision by the judicial authorities 49. It is emphasised in the report sent to the CPT by the Ministry of Public Order that police investigations are carried out under the direction and supervision of the public prosecutor's office. In this context, the CPT considers that regular visits by the competent judicial authorities to places of detention for which the police are responsible could make a significant contribution to the prevention of ill-treatment. The CPT would like to know whether the competent judicial authorities (in particular, public prosecutors) do in fact exercise such on-the-spot supervision of places of detention. h. persons detained under the Aliens legislation 50. As will become apparent from subsequent paragraphs, a significant number of the detainees encountered by the CPT's delegation in police establishments were being held under the Aliens legislation. The CPT would like to emphasise that the recommendations set out in this section of its report also apply to such persons. 51. The CPT would also like to receive information on the formal safeguards and practical arrangements which exist in order to ensure that aliens are not sent to a country where they run a risk of being subjected to torture or to inhuman or degrading treatment or punishment.