By Julien Toyer and Carlos Ruano
MADRID (Reuters) - Spanish Prime Minister Mariano Rajoy on Wednesday urged Catalonia to seek a constitutional reform to resolve its political problems with Madrid but he ruled out talks on a possible referendum on independence.
The public prosecutor's office meanwhile prepared to sue Catalan president Artur Mas on charges of disobedience and dishonesty after he defied a court injunction and held a symbolic vote on secession on Sunday.
"If what he (Mas) wants is to change the constitution to better fit into it...he has all the right to do so. He should have started from there," Rajoy told a news conference.
But Rajoy said he would oppose any reform that touched on national sovereignty and no talks could take place over a potential independence vote.
"I strongly believe in dialogue to solve political problems. But any dialogue should take place within the limits of the constitution," he said.
More than two million citizens Catalonians took part in a the non-binding vote on independence from Spain - billed as "citizen's consultation) on Sunday, reinforcing the wealthy northeast region's long-standing campaign for a break with the rest of Spain.
On Tuesday, Mas proposed the establishment of a permanent dialogue over Catalan independence and measures to boost the economy of the region, which accounts for about a fifth of Spain's population and economic output.
If the central government failed to address Catalonia's concerns, Mas said, then he would likely seek to bring forward the next regional elections due in late 2016 and use them as a proxy for a referendum on independence.
"That is what is on offer?," Rajoy said. "That if we don't do what Mr Mas says then he will call for elections. Is that the sort of dialogue we're being invited to?"
Mas, who lacks an absolute majority in the Catalan parliament, said such early elections would only be organized if Catalan parties could agree to run on a common platform.
He may however not be able to run himself as a complaint for disobedience and dishonesty set to be filed by Spain's public prosecutor could mean he is banned from it.
(Editing by Angus MacSwan)