extraditable offences between themselves. 7. Extradition shall be subject to the conditions provided for by the domestic law of the requested State Party or by applicable extradition treaties, including, inter alia , conditions in relation to the minimum penalty requirement for extradition and the grounds upon which the requested State Party may refuse extradition. 8. States Parties shall, subject to their domestic law, endeavour to expedite extradition procedures and to simplify evidentiary requirements relating thereto in respect of any offence to which this Article applies. 9. Subject to the provisions of its domestic law and its extradition treaties, the requested State Party may, upon being satisfied that the circumstances so warrant and are urgent and at the request of the requesting State Party, take a person whose extradition is sought and who is present in its territory into custody or take other appropriate measures to ensure his or her presence at extradition proceedings. 10. A State Party in whose territory an alleged offender is found, if it does not extradite such person in respect of an offence to which this Article applies solely on the ground that he or she is one of its nationals, shall, at the request of the State Party seeking extradition, be obliged to submit the case without undue delay to its competent authorities for the purpose of prosecution. Those authorities shall take their decision and conduct their proceedings in the same manner as in the case of any other offence of a grave nature under the domestic law of that State Party. The States Parties concerned shall cooperate with each other, in particular on procedural and evidentiary aspects, to ensure the efficiency of such prosecution. 11. Whenever a State Party is permitted under its domestic law to extradite or otherwise surrender one of its nationals only upon the condition that the person will be returned to that State Party to serve the sentence imposed as a result of the trial or proceedings for which the extradition or surrender of the person was sought and that State Party and the State Party seeking the extradition of the person agree with this option and other terms that they may deem appropriate, such conditional extradition or surrender shall be sufficient to discharge the obligation set forth in paragraph 10 of this Article. 12. If extradition, sought for purposes of enforcing a sentence, is refused because the person sought is a national of the requested State Party, the requested Party shall, if its domestic law so permits and in conformity with the requirements of such law, upon application of the requesting Party, consider the enforcement of the sentence that has been imposed under the domestic law of the requesting Party or the remainder thereof. 13. Any person regarding whom proceedings are being carried out in connection with any of the offences to which this Article applies shall be guaranteed fair treatment at all stages of the proceedings, including enjoyment of all the rights and guarantees provided by the domestic law of the State Party in the territory of which that person is present. 14. Nothing in this Convention shall be interpreted as imposing an obligation to extradite if the requested State Party has substantial grounds for believing that the request has been made for the purpose of prosecuting or punishing a person on account of that person's sex, race, religion, nationality, ethnic origin or political opinions or that compliance with the request would cause prejudice to that person's position for any one of these reasons. 15. States Parties may not refuse a request for extradition on the sole ground that the offence is also considered to involve fiscal matters. 16. Before refusing extradition, the requested State Party shall, where appropriate, consult with the requesting State Party to provide it with ample opportunity to present its opinions and to provide information relevant to its allegation. 17. States Parties shall seek to conclude bilateral and multilateral agreements or arrangements to carry out or to enhance the effectiveness of extradition. Article 17 Transfer of sentenced persons States Parties may consider entering into bilateral or multilateral agreements or arrangements on the transfer to their territory of persons sentenced to imprisonment or other forms of deprivation of liberty for offences covered by this Convention, in order that they may complete their sentences there. Article 18 Mutual legal assistance 1. States Parties shall afford one another the widest measure of mutual legal assistance in investigations, prosecutions and judicial proceedings in relation to the offences covered by this Convention as provided for in Article 3 and shall reciprocally extend to one another similar assistance where the requesting State Party has reasonable grounds to suspect that the offence referred to in Article 3(1)(a) or (b), is transnational in nature, including that victims, witnesses, proceeds, instrumentalities or evidence of such offences are located in the requested State Party and that the offence involves an organised criminal group. 2. Mutual legal assistance shall be afforded to the fullest extent possible under relevant laws, treaties, agreements and arrangements of the requested State Party with respect to investigations, prosecutions and judicial proceedings in relation to the offences for which a legal person may be held liable in accordance with Article 10 of this Convention in the requesting State Party. 3. Mutual legal assistance to be afforded in accordance with this Article may be