MADRID — Spain came under international pressure Monday to resolve a spiralling crisis with its Catalan region after a banned independence referendum was marred by shocking scenes of police violence.

The country’s central government vowed to stop its northeastern region breaking away from Spain after Catalonia’s leader claimed that 90 percent of voters backed independence in Sunday’s referendum, which Madrid says is unconstitutional and a "farce".

Abroad, the focus was on the violence which saw riot police move in on polling stations in towns and cities across the region to stop people from voting, in some cases charging with batons and firing rubber bullets to disperse crowds.

"We call on all relevant players to now move very swiftly from confrontation to dialogue. Violence can never be an instrument in politics,"

European Commission spokesman Margaritis Schinas said, breaking weeks of virtual EU silence on the Catalan issue.

UN rights chief Zeid Ra’ad Al Hussein said he was "very disturbed" by the violence and urged the Spanish authorities to ensure a thorough and impartial investigation, while EU President Donald Tusk urged Madrid to avoid "further use of violence".

The European Parliament will hold a special debate on Wednesday on the Catalonia referendum, the head of the assembly said.

Residents in many cities briefly stopped work at midday Monday and descended onto the streets in silent, solemn protest.

In Barcelona, municipal police said about 15,000 people stopped traffic as they rallied, many draped in the blue, yellow and red Estelada flag used by Catalan separatists, shouting "the streets will always be ours."

In another sign of the tensions, nearly 200 police were evicted from the hotel where they were staying after an angry crowd had demonstrated outside, shouting insults and some throwing bottles.

The main labour unions of Catalonia have called for a general strike Tuesday, which could disrupt flights and trains as well as the city’s port operations, saying they "vigorously condemn" the violence.

The city’s public universities are expected to join the strike, as is the contemporary art museum and the FC Barcelona football club. — AFP