Spain took drastic measures Saturday to stop Catalonia from breaking away, announcing plans to dismiss its separatist government and call fresh elections in a move the region's leader compared to the dictatorship of Francisco Franco.

Catalan president Carles Puigdemont and his ministers -- who sparked Spain's worst political crisis in decades by holding a banned independence referendum -- will be stripped of their jobs and their ministries taken over under measures laid out by Prime Minister Mariano Rajoy.

After hundreds of thousands of protesters flooded Barcelona's streets earlier Saturday to show their anger at Madrid, Puigdemont said Rajoy was guilty of "the worst attack on institutions and Catalan people" since Franco, calling for the parliament of the semi-autonomous region to meet urgently.

Franco ruled Spain with an iron fist from 1939 to his death in 1975, and among other repressive measures took Catalonia's powers away and banned the official use of Catalan language.

People hold a giant banner reading "Freedom for Jordi Sanchez! Freedom for Jordi Cuixart!" during a rally in Barcelona, to support two leaders of Catalan separatist groups who have been detained pending an investigation into sedition charges. Photo: AFP

Cautious, though, Puigdemont did not once say the word "independence" as Spain and the rest of the European Union waits to see if he will carry out his threat to declare a breakaway state.

Barcelona police said 450,000 people joined a protest in the regional capital earlier, many chanting "freedom" and "independence" and waving Catalonia's yellow, red and blue separatist flag.

Madrid could take direct control over Catalonia's police force and replace its public media chiefs, with Rajoy saying he had no other choice, faced with a grave threat to Spain's national unity.

Elections for the semi-autonomous region must be called within six months, he added.

The measures must now pass through the Senate -- a process that will take about a week -- but Rajoy's conservative Popular Party (PP) holds a majority there and his efforts to prevent a break-up of Spain have the backing of other major parties.

Spanish Prime Minister Mariano Rajoy said he had no choice but to take drastic measures against Catalonia's separatists. Photo: Reuters

The Catalonia crisis could cause a "dangerous dislocation", French Foreign Minister Jean-Yves Le Drian told the Journal du Dimanche, adding that he hoped the elections would "clarify the situation."

'The game could end badly'

Home to 7.5 million people, wealthy Catalonia fiercely defends its language and culture and has previously enjoyed control over its policing, education and healthcare.

Madrid has the power to wrest back control of rebellious regions under Article 155 of the Spanish constitution, but has never used it before.

Rajoy said the measure was a last resort as Puigdemont refuses to drop his threat to declare independence based on the results of the October 1 referendum, which had been ruled unconstitutional.

"This was neither our desire nor our intention," Rajoy said.

"We are applying Article 155 because the government of a democratic country cannot accept that the law is ignored."

Oriol Bartomeus, politics professor at the Autonomous University of Barcelona, said the central government was taking a huge risk.

"The game could end badly, very badly for Rajoy's government," he told AFP, adding civil servants and protesters could rise up against the measures.

"It's going to be like a colonial administration, and independence supporters will see it as an occupation."

Though she opposes the independence drive, Barcelona mayor Ada Colau deplored Madrid's decision, tweeting: "Rajoy has suspended the self-government of Catalonia for which so many people fought. A serious attack on the rights and freedoms of everyone."

Despite the political chaos in Catalonia, Barcelona's football team continued their merry way at the top of La Liga by beating Malaga 2-0 at the Camp Nou.

Other than the usual cries in favour of independence in the 17th minute to mark the fall of Catalonia in the Spanish War of Succession in 1714 and sporadic chants of "freedom", it was business as usual for Barca.

Elections by June

Allowing 54 days for campaigning, new elections would fall in mid-June at the latest.

Separatists of all political stripes, from Puigdemont's conservatives to the far-left, have dominated the Catalan parliament since the last elections in 2015, holding 72 seats out of 135.

Prosecutors said Saturday they would take former journalist Puigdemont to court for "rebellion" if he makes any attempt to declare independence, a crime punishable with up to 30 years in jail.

Puigdemont says 90 percent backed a split from Spain in the referendum, but turnout was given as 43 percent as many Catalans who back unity stayed away while others were hindered from voting by a police crackdown.

Catalonia is roughly evenly split over whether to go it alone, according to polls, with supporters saying the region pays too much into national coffers but their opponents arguing it is stronger as part of Spain.

The crisis has worried the EU as it struggles with Brexit and taken a toll on one of Spain's most important regional economies, with nearly 1,200 companies shifting their legal headquarters elsewhere in a bid to minimise the instability.