Clientlibs not loading the fonts when placed in apps

We have included the fonts using below syntax

@font-face {

  font-family: SlatePro-Bk;

  src: url("../css/fonts/SlatePro-Bk.woff") format("woff");

}

Font file is placed in apps/{project-folder}/clientlibs/{client-libraryfolder}/css/fonts/SlatePro-Bk.woff.

Fonts are not loaded it gives 404 error when the clientlib is rendered from apps using allowproxy= true. It is working fine when we move the clientlibraries to /etc/clientlibs.

Is this expected ? If yes, Do we have any other way to include the fonts/images in the clientlibrary?