In a televised speech late on Wednesday, regional president Carles Puigdemont condemned violence by police who tried to halt an independence referendum on Sunday that central authorities opposed. "We held the referendum amid an unprecedented repression and in the following days we will show our best face to apply the results of the referendum," Puigdemont said.
The separatist leader also called the government of Prime Minister Mariano Rajoy "irresponsible" for not accepting mediation in the deadlock, and criticized King Felipe VI for following what he said were the government's "catastrophic" policies toward Catalonia.
"You have disappointed many Catalans," Puigdemont told the king.
The Catalan parliament's secretary and attorney say that a planned plenary session to debate how the northeastern region's independence bid proceeds is unlawful and should be halted.
Catalonia's regional president, Carles Puigdemont, is addressing regional lawmakers on Monday to review a referendum won by supporters of independence from Spain on Oct. 1. The referendum and its legal framework had been put on ice by Spain's Constitutional Court, the reason why the parliament's legal counselors say the session should be halted.
Puigdemont says the vote, which took place amid police attempts to stop it that left hundreds injured, is valid and legitimates a declaration to break away from Spain.
The Spanish government says the vote was illegal and not valid, and blames Puigdemont for the violence.
Opposition parties have announced plans to appeal to the Constitutional Court to halt Monday's plenary session in the regional legislative.
Spain's main stock market index has lost more than 2.8 percentage points as shares of Catalan banks sank further amid certainty over how the region's secession bid proceeds.
The Ibex 35 index, which groups shares of the country's leading companies, sank below the 10,000 points mark for the first time in two years.
Shares of Caixabank decreased 5 percent and Banco Sabadell's 5.7 percent, but losses were spread across the Spanish banking industry. Telecommunications giant Telelefonica, fashion retailer Inditex and leading energy companies Repsol, Iberdrola and Gas Natural also suffered significant losses.
Biotechnology company Oryzon performed against the tide, its shares gaining nearly 13 percent after it announced late on Tuesday that it was moving its headquarters from Catalonia to Madrid.
Catalonia's president is due to speak later on Wednesday after secessionist regional lawmakers announced the region's independence declaration would be Monday. Spain opposes it.
European Commission Vice President Frans Timmermans says there is a "general consensus that regional government of Catalonia has chosen to ignore the law when organizing the referendum."
Timmermans was referring to the disputed independence vote Sunday in Catalonia, which the Spanish government in Madrid says violates the constitution. Spanish police left over 900 voters and others injured as they tried to stop the vote, and say over 400 police were left with bruises.
In a statement Wednesday to the European parliament, Timmermans said, in the 28-nation bloc, "respect for the rule of law is not optional, it is fundamental."
Timmermans also said "it is fundamental that the constitution of every one of our member states are upheld and respected."
The European Commission is appealing for dialogue between the Spanish government in Madrid and Catalonia even if it says there is a "general consensus" that the northeastern region ignored Spanish law with its referendum.
EU Commissioner Frans Timmermans on Wednesday called for both sides to talk to one another. He told legislators in Brussels "all lines of communication must stay open. It's time to talk, to find a way out of the impasse working within the constitutional order of Spain."
The separatist-run regional government has called for the European Union to intervene and mediate the dispute, but Timmermans seemed to rule that out.
He says "this is an internal matter for Spain that has to be dealt with in line with the constitutional order of Spain."
The far-left party CUP says Catalonia's regional parliament will consider a declaration of independence from Spain on Monday.
CUP parliament member Mireia Boya says the Catalan government plans to present the results of last Sunday's disputed referendum on Monday, which will trigger a declaration of independence.
Provisional results of the referendum that the Spanish government considers illegal showed the "Yes" side winning 90 percent of the 2.3 million votes cast, which is less than half the region's electorate. There was no organized campaign for "No" for the referendum, which Spain's highest court had suspended and was marred by police raids to confiscate ballot boxes that injured hundreds of voters.
Boya says "Oct. 9 will be the session . to declare the independence of Catalonia."
CUP is not a part of the Catalan government, which is formed by two mainstream separatist parties.
German officials say they are hoping for a "de-escalation" of the situation in Spain, but insist the conflict over Catalonia's independence drive is a domestic Spanish matter.
Asked about the Spanish police crackdown Sunday on people trying to vote in Catalonia's independence referendum, government spokesman Steffen Seibert said "it's absolutely not my role to evaluation police operations in Spain."
Seibert told reporters in Berlin on Wednesday that "it's the role of every government to uphold the democratic order," noting that Spain's constitutional court had previously declared the referendum to be in breach of the country's constitution.
He said Germany wasn't seeking to mediate in the dispute between Madrid and the regional government in Barcelona.
Catalonia's regional government is mulling when to declare the region's independence from Spain in the wake of a disputed referendum that has triggered Spain's most serious national crisis in decades.
The region's pro-independence president, Carles Puigdemont, who has said an independence declaration will come in a few days, is due to deliver a speech later Wednesday.
Spain, which declared Sunday's referendum illegal and invalid, is bitterly opposed to any independence move. Spain's conservative government has said it will respond with "all necessary measures" to counter Catalan defiance, and is holding talks with opposition leaders to forge a consensus over what to do in response.
In a special national address Tuesday night, Spain's King Felipe VI said Catalan authorities had deliberately bent the law with "irresponsible conduct."
Spain's National Court on Wednesday said it will quiz two senior officers of Catalonia's regional police force and the leaders of two pro-Catalan independence civic groups who have been placed under investigation for sedition.