Spain's government has vowed to block the semi-autonomous region of Catalonia from holding an independence referendum on November 9, 2014.
"The poll will not be held," Justice Minister Alberto Ruiz-Gallardon told journalists Thursday, just moments after Catalonia's President Artur Mas announced a deal among regional parties for the date and wording of a referendum.
Mas announced in the Catalan capital, Barcelona, that the referendum would ask the region's voters if they want Catalonia to be a state and, if so, should it be independent.
Mas did not clarify the distinction between a state and an independent state. However, the questions appeared to open a door for nationalists who want Catalonia to have the structure of a state but remain a part of Spain, possibly along the lines of Puerto Rico and the United States.
But Ruiz-Gallardon said the referendum would be unconstitutional and would not be allowed. Spokespersons for Spain's two largest political parties, the ruling Partido Popular (PP) and the left-leaning Partido Socialista Obrero Español (PSEO), also strongly condemned the planned referendum.
Alfonso Alonso, a PP spokesman, strongly criticized Mas, telling the Spanish daily El Mundo that "no referendum will take place" because "it doesn't fit within the law."
Spain's constitution says only the central government in Madrid can call a referendum, and Prime Minister Mariano Rajoy recently rejected a request by Mas to allow one. The government has not said what it might do to prevent a ballot.
Mas said the referendum date was set almost a year away so as to give ample time for negotiations with Madrid on "the way to stage the consultation legally."
Polls indicate that Catalans are roughly evenly split on the issue of independence. The European Union and NATO have warned Catalonia it would be excluded if it seceded.
Mas began pushing for a referendum after he failed to clinch a better financial pact for Catalonia with the central government in 2012. The referendum proposal received the support of some one million people who turned out at two demonstrations held since then.
The possibility of a region having the right to decide its future has stirred much political debate and raised questions as to whether it is time to reform the 1978 Constitution to ease territorial discontent.
The Basque region, which has traditionally sought greater powers, failed in a bid to hold a self-determination referendum several years ago.
Catalonia is one of the country's most powerful regions and represents roughly a fifth of Spain's $1.5 trillion GDP. Its population of 7.5 million is greater than those of EU members such as Denmark, Ireland or Finland.
The region, like others in Spain, has its own language in addition to Spanish. Its financial powers include some tax collecting rights.
Spain has 17 regions, each with substantial autonomy but with no control over key areas such as defense, foreign affairs, ports and airports, and in the making of national economic and financial decisions.
Elsewhere in Europe, Scotland is staging an independence referendum next year, on September 18. That vote has been approved by the UK government.
Al Jazeera and wire services