CATALAN separatist parties launched a new campaign for independence from Spain yesterday, hoping to win a majority in the regional parliament.

The Together for Yes bloc of nationalists has vowed to declare independence if they win a majority in the 135-member Catalan parliament.

The campaign for the September 27 ballot began on the same day as the Catalan National Day holiday that separatists have used for years to rally support in Barcelona for independence.

Catalan President Artur Mas, who also leads bloc member party Democratic Convergence of Catalonia, said: “I am willing to go to the end of this process if we have the majority of seats in parliament.”

Protesters clogged the city yesterday ahead of the late afternoon demonstration, many arriving by bus and train from remote parts of the region with pro-independence flags draped over their shoulders.

Organisers were hoping to attract at least 500,000 people under the slogan: “Let’s start building a new country.”

While the Spanish constitution forbids secession, Catalonia held a indicative independence referendum — dubbed a “participation process” — last year, in which 81 per cent voted in favour of leaving the Spanish state.

Catalonia has been part of Spain for hundreds of years but maintains its own language and national identity.

Such cultural expressions were suppressed under the 1939-75 Franco dictatorship, although the region saw a high level of economic development and is now one of the wealthiest in Spain.