By Nigel Davies
MADRID (Reuters) - An overwhelming majority in the powerful northeastern region of Catalonia want a referendum on independence, an opinion poll showed on Sunday, highlighting increasing dissatisfaction with Spain's central government as it struggles with economic crisis.
Although a referendum has been rejected by Madrid, which says it would be against the constitution, the poll published by La Vanguardia newspaper also showed a majority in favor of independence in Catalonia, one of Spain's richer regions.
With Catalans arguing they are unfairly treated by the central government and could better manage their finances on their own, the poll showed 81.5 percent wanted a referendum.
Fifty-three percent said they would vote in favor of independence, while 35 percent would vote against.
Prime Minister Mariano Rajoy reiterated on Saturday that a referendum could not be held as it would run counter to the constitution, introduced in 1978 to underpin Spain's transition to democracy after the death of dictator Francisco Franco.
Rajoy said in a speech in Barcelona, the regional capital, that Catalonia needed Spain as much as Spain needed Catalonia.
A secession is seen as unlikely by most analysts, but the demands for a referendum show the growing strains in Spain's post-Franco political consensus as the country struggles to cut debt while facing unemployment running at 25 percent.
Regional leader Artur Mas has called for an early election on November 25, after his claims for more fiscal autonomy were rejected by the central government last month.
The poll showed that were Catalonia to be given more control over its finances and have its own tax agency like that of the Basque Country then only 43 percent would still back a move towards independence.
It also showed that Mas' nationalist party Convergencia i Unio (CiU) would win the election comfortably with 40.9 percent of the vote.
The election will be an extra headache for Rajoy who is trying to reassure financial markets Spain can bring its budget and economy under control.
The poll showed Rajoy's People's Party winning 11.4 percent of the vote, down one percentage point from Catalonia's last election in 2010.
Protests have grown in Catalonia against cuts the country's 17 autonomous regions have been forced to make in education and healthcare, the two main areas they have control over.
The Catalan Socialist Party (PSC) would remain the second force in the region with 13.4 percent of the vote, a fall of five percentage points from the last election.
(Editing by Myra MacDonald)