Public prosecutors in Spain are expecting to press charges against the president of Catalonia, Artur Mas, in the coming days after he held a vote on secession from Spain in defiance of a court injunction, court sources have said.

The symbolic referendum, in which 2 million people voted, was described as “a deep failure” by Spain’s prime minister, Mariano Rajoy, on Wednesday.

Alicia Sánchez-Camacho, the head of the People’s party in Catalonia, said on Tuesday that the charges against Mas were “practically finished” and were expected to include disobeying a court order and misuse of government funds. Sánchez-Camacho said that Mas “had crossed a red line”.

Mas told the regional parliament that he wasn’t concerned about the charges, which might bar him from taking part in regional elections. “Can you imagine the image they would broadcast to the world if they acted against a government for putting out ballot boxes? It would be a dramatic image for Spain.”

Meanwhile, Rajoy called Sunday’s vote “a deep failure” and ruled out any possibility of a formal referendum on secession in the region.

The symbolic vote “was not a consultation or a democratic vote but rather an act of political propaganda,” he said. “Two out of three Catalans couldn’t even be bothered to participate.” He added: “In Catalonia, there are more Catalans than independentists. Catalonia is plural and Artur Mas can’t move forward with his initiative without provoking an enormous fracture within Catalan society.”

The north-eastern region was forced to water down its plans for a formal referendum after the central government in Madrid challenged its plans twice, resulting in two court-ordered suspensions of the vote.

Nevertheless, more than 2.3 million Catalans turned out on Sunday to vote, and four out of five voted to break away from Spain. The regional government said 5.4 million people were eligible to vote. The turnout, around 40%, has allowed for wide interpretations of the meaning of the vote.

Mas said his priority was now to secure a definitive referendum on independence for the region, similar to those granted to Scotland or Quebec. If he is unsuccessful, he said he would consider calling early elections that could act as a proxy referendum on secession.

For nearly a year, Rajoy has insisted that any vote on independence would be illegal. On Wednesday, he said his position remained unchanged. “It cannot happen. What was illegal a year ago remains illegal today,” he said, insisting that the Spanish constitution does not allow regions to take unilateral decisions on sovereignty.

He emphasised his readiness to enter into dialogue with Mas, but said he would not entertain any talk of a formal vote on independence. “That’s not dialogue. That’s an imposition,” he said, arguing that any dialogue must take place within the limits of the constitution.

Rajoy invited Mas to explore changing the constitution, a lengthy process that analysts say would likely be unsuccessful. “This is what he should have done from the beginning. It’s the only legal and responsible way to move forward with his plans.”