CDL-AD(2006)009 - 36 - Convention on Human Rights, as it is obliged to give priority to its jus cogens obligations, such as they ensue from Article 3. b) Active and passive co-operation by a Council of Europe member State in imposing and executing secret detentions engages its responsibility under the European Convention on Human Rights. While no such responsibility applies if the detention is carried out by foreign authorities without the territorial State actually knowing it, the latter must take effective measures to safeguard against the risk of disappearance and must conduct a prompt and effective investigation into a substantiated claim that a person has been taken into unacknowledged custody. c) The Council of Europe member State’s responsibility is engaged also in the case where its agents (police, security forces etc.) co-operate with the foreign authorities or do not prevent an arrest or unacknowledged detention without government knowledge, acting ultra vires. The Statute of the Council of Europe and the European Convention on Human Rights require respect for the rule of law, which in turn requires accountability for all form of exercise of public power. Regardless of how a State chooses to regulate political control over security and intelligence agencies, in any event effective oversight and control mechanisms must exist. d) If a State is informed or has reasonable suspicions that any persons are held incomunicado at foreign military bases on its territory, its responsibility under the European Convention on Human Rights is engaged, unless it takes all measures which are within its power in order for this irregular situation to end. e) Council of Europe member States which have ratified the European Convention for the Prevention of Torture must inform the European Committee for the Prevention of Torture of any detention facility on their territory and must allow it to access such facilities. Insofar as international humanitarian law may be applicable, States must grant the International Committee of the Red Cross permission to visit these facilities. As regards inter-state transfers of prisoners f) There are only four legal ways for Council of Europe member States to transfer a prisoner to foreign authorities: deportation, extradition, transit and transfer of sentenced persons for the purpose of their serving the sentence in another country. Extradition and deportation proceedings must be defined by the applicable law, and the prisoners must be provided appropriate legal guarantees and access to competent authorities. The prohibition to extradite or deport to a country where there exists a risk of torture or illtreatment must be respected. g) Diplomatic assurances must be legally binding on the issuing State and must be unequivocal in terms; when there is substantial evidence that a country practices or permits torture in respect of certain categories of prisoners, Council of Europe member States must refuse the assurances in cases of requests for extradition of prisoners belonging to those categories. h) The prohibition to transfer to a country where there exists a risk of torture or illtreatment also applies in respect of the transit of prisoners through the territory of