You need to provide a specific attestation issued by a Swiss representation, e.g. a certificate of nationality and registration.
In accordance with the Ordinance on Swiss Persons and Institutions Abroad, the Swiss representations abroad are authorised to provide attestations on the basis of established facts.
In this context Swiss representations are expected to check every request and to verify, among other things, if a local authority or institution is competent for drawing up a document and if Swiss interests are involved.
The Swiss representation concerned reserves the right to request additional information, and to refuse to draw up an attestation, if the document risks violating the sovereignty of a foreign state or could damage Switzerland’s reputation.
Ordinance on Swiss Persons and Institutions Abroad (Ordinance on Swiss Abroad; RS 195.11)