18. In the context of its monitoring activities of return fights, the CPT examined the treatment of foreign nationals during a removal operation by air from the Netherlands, co-ordinated and cofnanced by the European Agency for the Management of Operational Cooperation at the External Borders of the Member States of the European Union (FRONTEX). The monitoring took place in the context of an ad hoc visit to the Netherlands from 16 to 18 October 2013 and involved the presence of a CPT delegation on a charter fight to Lagos (Nigeria). In addition to the Netherlands, the Organising State, the following States took part in the FRONTEX mission: Bulgaria, Germany, Slovenia and Spain. Monitoring of the situation of persons convicted by international tribunals 19. One of these monitoring activities is regulated by an exchange of letters between the International Criminal Tribunal for the former Yugoslavia (ICTY) and the CPT dated 4 and 24 November 2000.3 Following the completion of its mandate, the ICTY was succeeded by the Mechanism for International Criminal Tribunals (MICT) on 1 July 2013 which is now responsible for supervising the enforcement of sentences rendered by the Tribunal. At present, the CPT has agreed to monitor the treatment and conditions of detention of any persons convicted by the ICTY who are serving their sentences in Albania, Portugal, Ukraine and the United Kingdom, as well as of certain persons convicted by the Tribunal and serving their sentences in Germany. 3. The exchange of letters is reproduced in the CPT’s 11th General Report; CPT/Inf (2001) 16, Appendix 5. As already indicated (see paragraph 8), during the ad hoc visit to Germany in November/December 2013, the CPT’s delegation monitored the situation of a prisoner sentenced to life imprisonment by the ICTY who is serving his sentence in Germany. 20. Another monitoring activity fows from an Exchange of Letters between the Residual Special Court for Sierra Leone and the CPT dated 20 January and 5 February 2014, and an Agreement between the United Nations and the United Kingdom Government, dated 10 July 2007. As already indicated (see paragraph 17), in the context of its ad hoc visit to the United Kingdom in November 2014, the CPT’s delegation examined the treatment and conditions of detention of one person convicted by the Special Court for Sierra Leone (SCSL). This visit was carried out on 18-19 November 2014. High-level talks with national authorities 21. It is standard practice for CPT visiting delegations to hold talks with the national authorities, at both the outset and the end of the visit. The end-of-visit talks usually involve the participation of Ministers and are the occasion for the delegation to present its preliminary observations. The CPT has also continued to seek to intensify its ongoing dialogue with certain states by means of high-level talks outside the framework of a given visit. Such talks have taken place on two occasions during the period covered by this General Report. 22. On 13 and 19 December 2013, representatives of the CPT had talks in Kyiv, Ukraine, with the Minister and Activities during the period 1 August 2013 to 31 December 2014 ► Page 13