Spain's government has rejected Catalonia's calls for self-determination after more than two million people took part in a symbolic vote on independence for the region.
Catalonia's leader Artur Mas has reached out to Madrid for talks on a "definitive" and binding vote, but the national government, which had tried to ban Sunday's ballot, is in no mood to oblige.
"The right to self-determination ... is not possible, neither under our constitution nor in any of the other democracies around us," Soraya Saenz de Santamaria, deputy prime minister, told parliament on Tuesday.
Demands for greater autonomy for the rich northeastern region have grown over recent years, spurred by Madrid's resistance and the recent economic crisis.
Catalonia accounts for a fifth of Spain's economy but also about six percent of its debts, according to official figures.
Mas said he had written to Mariano Rajoy, prime minister, on Tuesday inviting him "to set the conditions for a dialogue that is permanent and as constructive as possible".
The ultimate aim is to hold "a definitive and politically binding consultation" vote, Mas said.
Rajoy opposed Sunday's symbolic vote and has not reacted since the polls, in which 1.86 million people voted for independence.
Mas had hoped the vote would strengthen his hand in trying to force concessions from Rajoy, who has pledged to defend the unity of Spain as it recovers from recession.
Madrid has showed little sign of bending, with some members of the ruling Popular Party wanting to go after Mas in the courts.
"If what you want is independence for Catalonia, it will be difficult for us to come to an agreement," the deputy prime minister told the upper house Senate.
"Neither this party nor this government will vote for an agreement on secession."
Mas did not rule out calling a snap regional election to be fought exclusively on the independence issue.
He said he would hold talks over the coming weeks with other Catalan political parties to gauge support for such a move.
State prosecutors are meanwhile taking their time investigating whether Catalan authorities breached court injunctions by opening polling stations in public buildings.
Mas's regional government said on Monday that 2.3 million people took part in the vote, despite legal challenges and objections from the central government.
Anti-independence parties boycotted the referendum, saying the results would be skewed in favour of a break from Spain.
It was organised by pro-independence volunteers.
There was no official electoral roll but the regional government said 5.4 million of Catalonia's 7.5 million residents were eligible to vote.
Recent polls have indicated that about half of Catalans favour independence overall.