In article ,
says...
Thanks for the input chaps. No magic bullet then.......

Plan 'B'.

I'll try cutting a 6mm deep dado in the sides & screwing through from the
outside - hopefully the tight fit of the shelf in the dado will stop the
splitting.

Why not just glue it? I've made bookcases that way that held themselves
together even without glue, which makes the gluing up pretty easy.