The Catalan government has vowed to push forward with a symbolic vote on independence on Sunday, in defiance of a court order and the central government in Madrid.

“We will continue with the participative process,” the Catalan government spokesperson Francesc Homs said. “And we’ll do it with all the consequences.”

Homs said 40,000 volunteers had been recruited to stage the vote. Two questions will be put to Catalans: whether Catalonia should be a state, and if so, whether it should be an independent state.

His statement came shortly after Spain’s constitutional court announced it had agreed to hear the central government’s challenge of the watered-down vote. It was the second time in as many months that the court has acted to halt a planned Catalan vote on secession.

Three weeks ago, after several attempts to hold a non-binding vote within the confines of the law, the Catalan leader Artur Mas announced that the vote would be held in a modified way in an attempt to skirt legal restrictions. Sunday’s vote will now be a mostly symbolic one, staffed by volunteers and in which voters will register on the spot, in the absence of a formal electoral roll.

Spain’s prime minister, Mariano Rajoy, has repeatedly said any vote would be illegal as Spain’s constitution prevents any region from unilaterally taking decisions that affect all Spaniards.

Homs said the Catalan government would challenge the central government’s stance in the supreme court, “for violating the right to participation and the freedom of expression”. Polls suggest that a majority of Catalonia’s 7.5 million residents want a say on independence, and about half would vote to break away from Spain.

Campaigners have enlisted the support of the Nobel laureates Desmond Tutu of South Africa and Adolfo Pérez Esquivel, the Argentinian human rights campaigner, for a manifesto calling on the Spanish government to allow Catalans to vote.

Emilio Sáenz-Francés, a professor of history and international relations at Madrid’s Comillas Pontifical University, said that while the central government may have succeeded in watering down Sunday’s vote, it had done little to address the underlying grassroots movement pushing for independence.

“The real problem will start on 10 November,” he said, referring to the day after the vote. “You have a significant percentage of the population who feels that they were denied the right to vote. How do you manage this? How do you maintain the common project that is the nation of Spain? That’s the biggest challenge.”