-8Placing unaccompanied minors for several days or weeks in police stations or special holding facilities such as Amygdaleza or Petrou Ralli instead of providing them with accommodation in an appropriate shelter for juveniles is unacceptable. The Greek authorities should make every effort to end this practice. If exceptionally unaccompanied minors are deprived of their liberty as a last resort, additional safeguards should apply and they should only be held in suitable facilities with properly trained staff and an appropriate regime. Foreign nationals held under aliens legislation The actions taken by the Greek authorities in early 2015 such as the use of alternatives to detention, the limitation of the maximum period of detention to six months and the release of vulnerable groups, asylum seekers and long-term detainees have significantly reduced the number of persons held in pre-departure centres. However, the concept for the operation of pre-departure centres is still based on a security approach with detainees treated in many respects as criminal suspects. The Committee reiterates its recommendation that irregular migrants be held in centres specifically designed for that purpose, offering material conditions and a regime appropriate to their legal situation and staffed by suitablyqualified personnel. Further, urgent action should be taken to address the lack of any health-care staff at Corinth pre-departure centre. The conditions at Petrou Ralli Special holding facility remained totally inadequate for holding irregular migrants for prolonged periods, and the Committee makes recommendations to remedy the poor material conditions and lack of activities. The Greek authorities should also guarantee an integrated approach to the delivery of health care and put in place comprehensive procedures and training to monitor and prevent acts of self-harm and attempted suicides.