Spain’s King Felipe VI has condemned organisers of Catalonia’s independence referendum for having put themselves “outside the law”.
In a TV address to the nation, he said the situation in Spain was “extremely serious”, and called for unity.
Hundreds of thousands in Catalonia have been protesting over Spanish police violence during Sunday’s vote, during which nearly 900 people were hurt.
The central government in Madrid has described the referendum as illegal.
During the vote, 33 police officers were also injured, local medical officials said.
In his address, King Felipe VI said Catalan leaders who organised the referendum showed their “disrespect to the powers of the state”.
“They have broken the democratic principles of the rule of law.
“Today, the Catalan society is fractured,” the king said, warning that the poll could put at risk the economy of the wealthy autonomous north-eastern region and the whole of Spain.
But he stressed that Spain “will overcome difficult times”.
Huge protest rallies have been taking place across Catalonia.
In Barcelona alone, 700,000 people took to the streets, city police were quoted as saying by the AFP news agency.
This has not been confirmed by the authorities in Madrid.
More than 50 roadblocks in the city caused big traffic jams. Barcelona’s metro traffic was cut to a 25% service during rush hour and no trains at all at other times.
Barcelona’s port was at a standstill, trade union sources said.
Top tourist attractions were also closed, including the city’s famous Sagrada Familia church.
Mercabarna – Barcelona’s massive wholesale market – was left deserted as some 770 food businesses closed for the day.
However, the city’s El Prat airport and its taxis are operating normally.
Many small businesses have shut for the day. Schools, universities and medical services were also closed or operating at a minimum level.
The strike was called in protest at “the grave violation of rights and freedoms” seen during Sunday’s ballot.
Some police officers were seen firing rubber bullets, storming into polling stations and pulling women by their hair.
Spanish Prime Minister Mariano Rajoy has said the vote made a “mockery” of democracy.
Earlier on Tuesday, Spanish Interior Minister Juan Ignacio Zoido said: “We see how day after day the government of Catalonia is pushing the population to the abyss and inciting rebellion in the streets.”
He also warned that the central government would take “all measures necessary to stop acts of harassment”.
Meanwhile, Deputy Prime Minister Soraya Sáenz de Santamaría condemned the “mafia” behaviour of those protesters who had earlier gathered around hotels housing Spanish police officers and demanded that they leave.
On Sunday, more than 2.2 million people reportedly voted in the referendum. The Catalan government says the vote in support of independence was nearly 90%, but official results have not yet been released.
Turnout was relatively low at a reported 42%, potentially weakening the position of Catalan leader Carles Puigdemont.