(CNN) Catalonia's leader has launched a strongly worded attack on the King of Spain for failing to heal the country's divisions after a bitterly contested independence referendum.

In a TV address from the headquarters of the Catalan government in Barcelona on Wednesday, Catalan President Carles Puigdemont said King Felipe had missed an opportunity to mediate in the political and constitutional crisis that has engulfed the country.

The King delivered a stern warning in a TV address on Tuesday, saying Catalan leaders had acted "outside the law" and accusing them of "unacceptable disloyalty" for pressing ahead with their moves toward secession.. Catalonia is an autonomous region of Spain, located in the northeastern part of the country.

Puigdemont said the Spanish monarch "ignores millions of Catalans who think in a different way" to the central government of Prime Minister Mariano Rajoy.

"You disappointed many people in Catalonia who appreciate you and are expecting a call to dialogue," Puigdemont said after the King's hard-line remarks.

The King has a constitutional duty to arbitrate when there is a diplomatic dispute, Puigdemont said.

"We need mediation," he said. "This conflict needs to be resolved in a political way, not with police."

He directed parts of his address to Spaniards in other parts of the nation, to the King and to Catalonians.

Urging calm

Puigdemont is expected to formally declare independence on Monday, after 90% of voters in last Sunday's referendum opted for a split. The vote was marred by clashes between citizens and Spanish police.

Puigdemont urged calm.

"Let's not allow other people to provoke us. Let's not fall into provocations of violence," he said.

Puigdemont said that while others say the vote was illegal, Catalonia will follow "a democratic way" that should be respected.

The Spanish government on Wednesday said it "strongly rejects the accusations" Puigdemont directed at the King.

"These accusations show that Mr. Puigdemont not only is against the law, but also is outside reality," the government said.

"Tonight he lost every opportunity to bring Catalonia back to the path of coexistence within the law. Far from that, he went one step further in his path to radicalization, isolation and defiance of institutions."

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Puigdemont's remarks came as the Catalans' standoff with Madrid deepened Wednesday. Spain's highest court summoned the chief of the Catalan police to answer accusations of sedition, or provoking a rebellion against the state.

Josep Lluís Trapero was called to testify in Madrid on Friday: Spanish authorities believe Trapero's 17,000-strong force did not do enough to prevent the banned referendum from taking place. Sedition by public officials carries a 15-year sentence in Spain.

He was ordered to appear with three others: his deputy Teresa Laplana and the leaders of pro-independence groups Catalan National Assembly and Omnium Cultural, Jordi Cuixart and Jordi Sanchez.

Protesters joined by firefighters raise their hands as they gather during a general strike in Barcelona Tuesday.

Puigdemont is due to address the Catalan Parliament on Monday, in a session called to "discuss the results of the referendum on October 1 and its effects," a statement from the parliament said.

It will be Puigdemont's first opportunity to make a formal declaration of independence under the Catalan referendum law that was ruled illegal by Spain's top court.

Such a move would severely test the government of Prime Minister Rajoy. If Madrid decides that Catalonia is acting unconstitutionally, Rajoy could invoke emergency powers to take control of the Catalan government.

That would almost certainly require officers from the Guardia Civil, the national security force, to be deployed again on the streets of Catalonia. Thousands are on standby in the port of Barcelona, and their redeployment would be highly provocative after they led a violent crackdown of Sunday's referendum.

Business groups rattled

The prospect of a rupture in Spain's young democracy -- the dictatorship of Francisco Franco ended only in 1975 -- has rattled business groups.

The Spanish business lobby group, Cercle d'Economia, said it was concerned by the prospect of a declaration of independence and called for both sides to start talks.

"Such a declaration would plunge the country into an extraordinarily complex situation with unknown, but very serious consequences," the group said in a statement reported by Reuters Wednesday.

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The developments have also alarmed the European Union, which has so far supported Madrid.

Speaking at a debate on Catalonia in the European Parliament on Wednesday, European Commission Vice-President Frans Timmermans called for dialogue. "All lines of communication must stay open. It's time to talk to find a way out of the impasse," he said.

Timmermans backed the Spanish government's stance: "This is an internal matter for Spain that has to be dealt with in line with the constitutional order of Spain," he said.

But he lamented Sunday's events, when the Guardia Civil raided polling stations, fired rubber bullets and dragged people out of voting centers. "Violence does not solve anything in politics," he said.

The referendum and its aftermath has split Catalans. Some 90% of voters backed a split from Spain, but turnout was only around 42%, largely because anti-independence Catalans did not show up.

Barcelona taxi driver Ana Maria Lopez, who opposes a split, said Puigdemont "thinks he's a king" and said a declaration of independence would be meaningless: "Him declaring independence is like me declaring 'from tomorrow I'm a princess,' " she told CNN.

But like many in Catalonia, she was critical of the central government in Madrid, saying its poor handling of the situation had made things worse.

Anti-independence groups staged a small demonstration in Barcelona on Wednesday evening.

About 200 people gathered in front of Spanish government buildings and chanted"You are not alone" and "This is our police" to the officers from the Spanish National Police and Guardia Civil who guard the buildings.