The president of Spain's regional government of Catalonia has said he wants to hold an independence referendum on November 9, 2014, but the Spanish government immediately said no.
Artur 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.
Mr Mas did not clarify the distinction between a state and an independent state. However, the questions appeared to open a door for those 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.
Justice Minister Alberto Ruiz Gallardon responded to Mr Mas' announcement, saying a referendum would be illegal and would not be allowed.
Spain's Constitution says only the central government in Madrid can call a referendum, and Prime Minister Mariano Rajoy recently rejected a request by Mr Mas to allow one. The government has not said what it might do to prevent a ballot.
Mr 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 independence. The European Union and Nato have warned Catalonia it would be excluded if it seceded.
Scotland is staging an independence referendum next year, on September 18. That vote has been approved by the British government.
Mr 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 got 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 1.1 trillion euro (£930 bn) 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 as well as 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 defence, foreign affairs, ports and airports, and in the making of national economic and financial decisions.