Cantabria regional president, Miguel Ángel Revilla (archive photo), has promised to investigate the origin of a toxic spill that killed nearly a tonne of fish in Besaya river near Cartes.

Describing the incident as an "ecological disaster," Mr Revilla said that the toxic substance responsible "seems to be some kind of ammonia."

For his part, regional Rural Development minister, Jesús Oria, confirmed that the remainder of the dead fishes - mostly nase, minnow as well as some large trout - should be recovered by the end of today, and that they are being taken to the Meruelo garbage disposal facility for incineration.