El Pais sets out most clearly the Spanish position;
As things stand today, the Spanish Constitution does not contemplate the right to secession. It obliges all powers to preserve the unity of the state and to guarantee that sovereignty will remain in the hands of all Spaniards.And there you have it; Spain is indivisible, self-determination, even for a population that meets international criteria for a separate people, will not be permitted. With all offers of external mediation rejected, and Catalans not given the slightest hope of a legal referendum, Catalan leaders are being forced into an unlawful and unwarranted declaration of independence, or abject surrender to Madrid's rule.
Accepting a dialogue, mediation or negotiation that might lead to a legal, agreed-to referendum with a binding option for Catalan secession from Spain entails opening up a negotiation for constitutional reform between the governments of Spain and Catalonia, and this is something that the central government cannot do unilaterally, much less under pressure or through international mediation.
The only body that can reform the Constitution is Congress – where Catalans are also represented, by the way. To this should be added all the citizens of Spain, who would have to be consulted in a national referendum.
This is not the way to deal with devolution in the 21st century. Even at this hour I hope calmer heads will prevail to avert what would be a catastrophe for the peoples of Spain and Catalonia.