More than a million people have gathered on the streets of Barcelona demanding independence for Catalonia from the rest of Spain, police say.
A human sea flooded the city on Tuesday as Catalans waved red-and-yellow striped Catalan flags and marched for the region's national day, the Diada, many accusing Spain of dragging them into economic trouble.
"There are 1.5 million people and everything has gone peacefully," a police spokesman said.
Closely watched by other independent-minded regions in Europe such as Scotland and Flanders, the Catalans rallied under the slogan: "Catalonia, a new European state".
"What do the crowds want? A new European state. What do the people want? An independent Catalonia," they chanted, packing the northeastern region's capital.
About 1,000 buses ferried protesters from across the northeastern Spanish region.
Fiercely proud of their distinct language and culture, Catalans increasingly feel they are getting a raw deal from Madrid and their president is now demanding the right to raise and spend their own taxes.
"If there is not an agreement on the economic basis, you know that the way of Catalonia for freedom is open," Catalonia's regional leader Artur Mas said in English at a news conference.
"My goal is to try to reach an agreement with the central government on the economic area and to try to protect Catalonia and to give our country the tools we need to build our future, our national future," Mas said.
Catalonia, whose economy is bigger than Portugal's, accounts for a fifth of Spanish output. But it is being squeezed by austerity cuts and by an economic crisis that has put one in four people out of work across the country.
Mas, leader of the pro-autonomy Convergence and Union alliance, argues that the region gives far more to the rest of Spain than it receives.
The Catalan leader is to discuss the so-called fiscal pact with Mariano Rajoy, Spain's prime minister, on September 20.
"There is no battle more pressing, no challenge more important than attaining fiscal sovereignty for our country. And never more so than this very moment," Mas said on the eve of the march.
He said he could not join the march himself because of his "institutional" role representing all Catalans.
"Nevertheless, even being absent, I want you to know that your demands are my own, your voice is my own and your desires my own," Mas said.
Last month, the region reached out for a 5bn euro ($6.4bn) central government rescue so as to make repayments on its 40bn euro debt, equal to a fifth of its total output. But the Catalan government says the region is just asking for its own money back.
A survey taken in July and published in Barcelona-based newspaper La Vanguardia on Sunday showed 51.1 per cent of people in Catalonia in favour of independence, compared to just 36 percent in 2001.
Rajoy and his conservative Popular Party government insist that fiscal autonomy for Catalonia will do nothing to resolve the economic crisis.
The only path, Rajoy says, is to slash the public deficit for the central government and in the regions, on which Madrid has imposed a deficit limit equal to 1.5 per cent of economic output this year.
Catalonia posted a deficit of 3.9 per cent of its output last year, contributing to the nation's overall deficit of 8.9 percent - a figure that alarmed world financial markets.
"If at any time in Spain's recent history it has been important to work together for a goal, which is to improve prosperity and the well-being of citizens, to create jobs, to confront the crisis and to resolve it, I think that moment is now," Rajoy said on Tuesday.