Spain's prime minister has called a referendum on independence for Catalonia "illegal" in his state of the union address.
Mariano Rajoy vowed to block the vote, which the Catalan authorities intend to hold on 9 November.
Both Spain's ruling conservative party and the Socialist opposition have long stated their rejection of a referendum.
But in recent months, the Catalan regional government has vowed to press ahead even without Madrid's blessing.
Mr Rajoy told the Spanish parliament during the annual state of the nation debate that "this referendum can't take place, it is not legal".
He added: "It is the entire Spanish people who have the capacity to decide what Spain is."
Mr Rajoy also addressed Spain's economic problems in his speech, saying that the country had turned a corner and was "part of the driving engine" of Europe.
He also revised the growth forecast upwards from 0.7% to 1% for 2014, and promised tax cuts for 12 million of Spain's 17 million taxpayers.