A/HRC/7/4 page 5 Introduction 1. Working Group on Arbitrary Detention was established by the former Commission on Human Rights in its resolution 1991/42 and entrusted with the investigation of instances of alleged arbitrary deprivation of liberty, according to the standards set forth in the Universal Declaration of Human Rights and the relevant international instruments accepted by the States concerned. The mandate of the Working Group was clarified and extended by the Commission in its resolution 1997/50 to cover the issue of administrative custody of asylum-seekers and immigrants. At its sixth session the Human Rights Council assessed the mandate of the Working Group and adopted resolution 6/4 which confirmed the scope of its mandate and extended it for a further three-year period. 2. During 2007, the Working Group was composed of the following experts: Manuela Carmena Castrillo (Spain); Soledad Villagra de Biedermann (Paraguay); Leïla Zerrougui (Algeria); Tamás Bán (Hungary) and Seyed Mohammad Hashemi (Islamic Republic of Iran). 3. On 30 November 2007, Leïla Zerrougui was confirmed as Chairperson-Rapporteur of the Working Group and Manuela Carmena Castrillo was appointed as the Working Group’s Vice-Chairperson. I. ACTIVITIES OF THE WORKING GROUP IN 2007 4. During the period 1 January to 30 November 2007, the Working Group held its forty-eighth, forty-ninth and fiftieth sessions. It also carried out official missions to Norway (22 April-2 May 2007), Equatorial Guinea (8-13 July 2007) and Angola (17-27 September 2007) (see addenda 2, 3 and 4). A. Handling of communications addressed to the Working Group during 2007 1. Communications transmitted to Governments 5. A description of the cases transmitted and the contents of the replies of Governments will be found in the relevant Opinions adopted by the Working Group (A/HRC/7/4/Add.1). 6. During its forty-eighth, forty-ninth and fiftieth sessions, the Working Group adopted 40 Opinions concerning 146 persons in 24 countries. Some details of the Opinions adopted during that session appear in the table below and the complete texts of Opinions Nos. 1/2007 to 13/2007 and 32/2007 to 47/2007 are reproduced in addendum 1 to the present report. 2. Opinions of the Working Group 7. Pursuant to its methods of work,1 the Working Group, in addressing its Opinions to Governments, drew their attention to Commission on Human Rights resolutions 1997/50 and 1 E/CN.4/1998/44, annex I.