LibreOffice Draw is a vector editing program including tools for flowcharts and diagrams. Draw can import graphics in all the commonly-used formats (including BMP, GIF, JPEG, PNG, TIFF, and WMF). Draw can also export to Flash (.swf) format.
SVG images not ok
We have experience problems when importing SVG images created in LibreOffice Draw into Scribus.
The solution is to import them into Inkscape first, clean them up (if necessary) and save them.