Madrid - Spain's government on Tuesday warned against regional elections in Catalonia being used to promote its independence.Catalan Premier Artur Mas set himself on a collision course with Madrid on Monday night by calling early elections for the regional parliament for September 27 and labelling them a referendum on independence from Spain."Nobody will break up Spain, not by any means," Prime Minister Mariano Rajoy said."This election serves one purpose and one purpose only, to elect a new regional parliament," Rajoy said.Mas' Democratic Convergence party, its allies in the Republican Left of Catalonia and three other parties without parliamentary representation forged an electoral alliance and negotiated a common list of candidates, including Bayern Munich coach Pep Guardiola.According to their agreement, if the separatists win the September polls, they plan unilaterally to declare Catalonia's independence within 18 months.Regional elections had been expected in late 2016. Mas said the September 27 poll would take on a "plebiscite character"."The date will go down in the history of Catalonia," Mas said in Barcelona.While rejecting the idea that the regional elections constitute a referendum, Rajoy did say that they should be decisive and that the pro-Spanish parties should deliver the separatists a crushing blow and end talk of independence once and for all."The current situation cannot persist," he said. "The election must end the division and discord [in Catalan society]."The Catalonian government failed in its attempt in November 2014 to hold a referendum on separating from Spain. The Spanish constitutional court blocked the vote in response to a petition by the central government. An unofficial vote was held on November 9.Mas, who used to be considered a moderate technocrat, became more radically separatist after Madrid refused to give Catalonia tax-raising powers, like those the Basque region has had for years.Not all of Mas' usual allies agree with a unilateral declaration of independence with some even distancing themselves from the idea, including the left-wing separatist Popular Unity Candidates, which did not join the electoral pact. The Christian Democrats also split from a decades-old pact with Mas' party over the issue.Recent opinion polls also showed slightly more Catalans against independence than for it. Only nine months earlier, 80.7% of voters had cast ballots for secession in the non-binding referendum.The Spanish government has repeatedly insisted that it would not allow Catalonia to become independent.The north-eastern region is richer than other parts of the country, and its residents have charged that they have been called on to provide support during the years of Spain's financial downturn.