Article 28 1. The present Protocol shall enter into force on the thirtieth day after the date of deposit with the Secretary-General of the United Nations of the twentieth instrument of ratification or accession. 2. For each State ratifying the present Protocol or acceding to it after the deposit with the Secretary-General of the United Nations of the twentieth instrument of ratification or accession, the present Protocol shall enter into force on the thirtieth day after the date of deposit of its own instrument of ratification or accession. Article 29 The provisions of the present Protocol shall extend to all parts of federal States without any limitations or exceptions. Article 30 No reservations shall be made to the present Protocol. Article 31 The provisions of the present Protocol shall not affect the obligations of States Parties under any regional convention instituting a system of visits to places of detention. The Subcommittee on Prevention and the bodies established under such regional conventions are encouraged to consult and cooperate with a view to avoiding duplication and promoting effectively the objectives of the present Protocol. Article 32 The provisions of the present Protocol shall not affect the obligations of States Parties to the four Geneva Conventions of 12 August 1949 and the Additional Protocols thereto of 8 June 1977, nor the opportunity available to any State Party to authorize the International Committee of the Red Cross to visit places of detention in situations not covered by international humanitarian law. Article 33 1. Any State Party may denounce the present Protocol at any time by written notification addressed to the Secretary-General of the United Nations, who shall thereafter inform the other States Parties to the present Protocol and the Convention. Denunciation shall take effect one year after the date of receipt of the notification by the Secretary-General. 2. Such a denunciation shall not have the effect of releasing the St ate Party from its obligations under the present Protocol in regard to any act or situation that may occur prior to the date on which the denunciation 102