A court on Tuesday summoned Mas to face possible charges for holding a 2014 symbolic ballot on Catalan independence, which is fiercely opposed by Madrid.
The case dates back to last year but the summons came just two days after separatist groups won an absolute majority in the Catalan parliament in a separate regional election.
“It was the reaction of a proud government whose pride was hurt, a rabid, clumsy one incapable of dialogue, which acts brutishly and is doing all it can to try to get rid of me,” Mas said in a radio interview.
Spanish Prime Minister Mariano Rajoy rejected Mas's claims of victory in Sunday's election, in which Mas and fellow separatists won control of the regional parliament but fell short of an absolute majority of votes.
The separatists claimed Sunday's regional election result gave them a mandate to push on towards a declaration of independence by 2017.
The Catalonia high court on Tuesday called Mas to go before a judge on October 15th for questioning on accusations of civil disobedience, abuse of power and embezzlement of public funds in last year's vote.
He and two other officials are accused of breaking the law by organizing the ballot on November 9th in defiance of an injunction by Spain's Constitutional Court. If found guilty, they could be banned from public office.
Mas told Catalunya Ràdio that the November vote was “a great act of democratic rebellion”.
“Legally I did not disobey; politically it was a democratic rebellion against the Spanish state. I just took out the ballot boxes,” he insisted.
Catalan nationalists say they get a raw deal from the central government which redistributes their taxes.
Mas said he was ready for dialogue with Madrid, but Rajoy has refused any talks on independence.
Rajoy has rejected their calls for greater autonomy and called for unity as the eurozone's fourth-biggest economy recovers from recession.
In order to form a pro-independence parliamentary bloc, Mas's Together For Yes alliance must team up with the radical left-wing group CUP, which has said it will refuse to accept him as leader of the separatist movement.
With both parties set to start negotiations imminently, Mas called on the CUP to “join forces against an arrogant adversary that does not want dialogue”.
Catalan leaders could find themselves with new interlocutors in Madrid depending on who wins Spain's general election in December.