1.Each Member State shall take the necessary measures to ensure that in the execution of an EIO the issuing authority and the executing authority take due account of the confidentiality of the investigation.
2.The executing authority shall, in accordance with its national law, guarantee the confidentiality of the facts and the substance of the EIO, except to the extent necessary to execute the investigative measure. If the executing authority cannot comply with the requirement of confidentiality, it shall notify the issuing authority without delay.
3.The issuing authority shall, in accordance with its national law and unless otherwise indicated by the executing authority, not disclose any evidence or information provided by the executing authority, except to the extent that its disclosure is necessary for the investigations or proceedings described in the EIO.
4.Each Member State shall take the necessary measures to ensure that banks do not disclose to the bank customer concerned or to other third persons that information has been transmitted to the issuing State in accordance with Articles 26 and 27 or that an investigation is being carried out.