Answer
A Russian internal passport is not required to obtain a Russian international passport at a consulate. An international passport can be obtained through a consular office by appointment, even if you do not have your internal passport with you.
The absence of an internal passport does not mean that the consulate does not need proof of identity and citizenship. It is worth showing all available Russian documents: a valid or expired international passport, a birth certificate, documents confirming a change of surname, and other records if they clarify the information in the application form.
It is safer to treat an internal passport as possible supporting evidence rather than the sole requirement for the service. The exact set of documents depends on age, the type of international passport, whether a valid document is available, and whether citizenship needs to be verified. If the documents differ in given name, surname, or transliteration, it is best to clarify this before booking an appointment.