BARCELONA (AFP) - Catalonia's nationalist government vowed to step up its secession drive after more than two million people voted Sunday in a symbolic independence referendum which Spain's central government dismissed as "useless".

Catalan government head Artur Mas called the vote, which was ordered blocked by the constitutional court at Madrid's request, "a total success" after the overwhelming majority of those who took part supported independence.

"Catalonia has once again, the people of Catalonia, have made it very clear that we want to govern ourselves. It is an old aspiration, which dates back centuries and remains perfectly alive," he added in Barcelona after polls closed.

Preliminary results released by the Catalan government showed 80.7 percent of participants - or about 1.6 million people - voted for independence.

Anti-independence parties largely boycotted the referendum, which was organised by an army of volunteers, skewing the results in favour of a break from Spain.

The government also forecast that final turnout figure would be 2.25 million voters despite legal challenges and objections from the central government in Madrid to the ballot.

"We have been asking for this for a long time. While it is not official we can finally express what we feel. If we really want change, we have to do something," said 19-year-old student Maria Arbaizar as she voted at a Barcelona school.

There was no official electoral roll but the regional government said 5.4 million Catalans and resident foreigners aged 16 and above were eligible to vote.

"Sovereigntist flood," Catalan daily El Periodico wrote on its front page above a picture of a long line of voters waiting to cast ballots at a school gym.

"Success at the ballot box strengthens and speeds up the separatist process," wrote rival Catalan daily Ara.

Mas said his government would now push to hold an official referendum and would seek international support to help persuade the Spanish government to allow it to go ahead.

"We deserve to vote in a legal and binding referendum and this is what we are going to try to do," he added.

Mas had originally planned to hold an official yet non-binding vote on independence, inspired by the referendum held in Scotland in September which resulted in a "No" vote.

But the Spanish government's legal challenges forced him to water that down.

Justice Minister Rafael Catala dismissed the vote as "fruitless and useless" and said it was "devoid of any kind of democratic validity".

State prosecutors were continuing to investigate whether Catalan authorities breached court injunctions by opening polling stations in schools and other public buildings, he added.

Analysts said the turnout did not show there was enough support for outright independence.

The total number of votes in favour of independence was below the number won in the last regional elections in 2012 by the four Catalan nationalist parties which called the referendum, said Gabriel Colome, political science lecturer at Barcelona's Autonomous University.

"They expected to get much more. This means that in a hypothetical real referendum they have a problem," he said.

If Mas opts to hold early elections, the symbolic referendum results indicate that nationalists parties will not be able to secure a majority in the regional assembly that would allow them unilaterally declare independence as some have proposed, he added.

Political scientist Fernando Vallespin of Madrid's Autonomous University said the referendum was a "a relative victory" for independentists.

"It shows that Catalans want to vote. But it is a long way from showing that they want independence," he told AFP.

Proud of its distinct language and culture, Catalonia, a region of 7.5 million people, accounts for nearly a fifth of Spain's economy.

Demands for greater autonomy have been rumbling for years, but the latest bid has pushed the issue further than ever before.