Thompsons Solicitors said relatives should have been told that former Lord Advocate Dame Elish Angiolini's investigation into the former practices at Mortonhall Crematorium had been delivered on Monday, April 14.
They issued a strongly worded statement last night shortly after Edinburgh City Council chief executive Sue Bruce confirmed she would be writing to the affected families in the coming days.
Solicitor Patrick McGuire said: "The families and myself are stunned that we learned this news through reports in the media.
"My clients are bereaved parents who have been to hell and back over this whole business and they expect to be treated in a sympathetic and decent manner.
"Being kept properly informed is the least they could expect."
No date has been set for publication.