If there is one single band that Nàda can most easily be compared to, it has to be Swans; whilst "Celmètra" can be likened to Swans' early period ("Filth" to "Children of God"), then "Ùr" is comparable to their later work ("Children of God" to "The Great Annihilator"). The early primal raw power has been channelled into a more focussed hypnotic sound. Nàda's music is much more positive in feel than that of Swans, however.
Other suitable points of reference would be Neurosis, plus tribal post-punk acts like Killing Joke, The Banshees and Ausgang. Also prominent is an increased use of ethnic percussion and instrumentation, with mesmerising tribal polyrhythms that actually sound authentic.
This is a phenomenally good album, and I can't understand why it isn't better known.
Nàda -- "Ùr" CD (1997)
For the sake of the search engines out there, here are the names without accents: Nada Ur Celmetra