Catalan leader Artur Mas vowed to step up the push for independence after early results from Sunday's symbolic vote showed that four out of five voters in the region backed breaking away from Spain.
With more than 2m votes cast, Mas called the symbolic referendum a "lesson in democracy, spelled out in capital letters". He said he would send a letter on Monday to Spain's prime minister, Mariano Rajoy, urging him to confront "the Catalan question" with a formal, binding referendum on independence.
"We want to decide a new political future. All nations have a right to do so and mature democracies respect that," said Mas.
After months of tense legal wrangling between Madrid and Barcelona, Catalan leaders were forced to water down their plans for a formal referendum and turn it into a symbolic vote, staffed by 41,000 volunteers and voters who registered on the spot.