Exporting vector graphics from Inkscape into Libreoffice

Exporting from Inkscape using the png image format which Libreoffice fully supports, rather than saving in vectorial format which it does not support, is actually the only option.

See in Inkscape Wiki : Save as vs export.

However, the thread How to import SVG in OOo Writer says :

The svg import will be new feature in OOo 3.4, try OOo 3.4 beta from OOo download site.

This is about OpenOffice, of which Libreoffice is actually another branch.
You might consider changing because of this feature, until it finds its way into Libreoffice.