A crowd with Spanish flags pack Plaza del castillo square during a protest called by Spain's Conservative Popular Party in Pamplona, northern Spain, Nov 12, 2023. (PHOTO / AP)

MADRID - Tens of thousands of people protested across Spain on Sunday against acting prime minister Pedro Sanchez's plans to grant amnesty to Catalan separatists in exchange for support for another term in office.

The government secured a deal with Catalan separatist party Junts on Thursday which includes passing a contentious law granting amnesty to those convicted over Catalonia's attempt to secede from Spain in 2017.

The deal sent shockwaves around the country, with Sanchez's conservative opponents accusing him of putting the rule of law on the line for his own political gain.

"We will not shut up until there are new elections," People's Party (PP) leader Alberto Nunez Feijoo told a cheering crowd packed into Madrid's Puerta del Sol square.

In Barcelona, local police said 6,000 people demonstrated, while numbers reached 30,000 in Granada and 50,000 in Seville according to authorities

Authorities said 80,000 people turned out in Madrid while the PP, which had called for protests in cities across Spain, put the total closer to one million.

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Many held Spanish and EU flags, as well as banners with slogans including "respect the Constitution".

"He (Sanchez) has betrayed coexistence, democracy...he can't keep governing," said banker Tomas Perez, 38, holding a sign reading "Sanchez traitor".

"Many people that I know who vote for the Socialists feel absolutely disappointed because... Sanchez never said the amnesty would be part of his program," said Inmaculada Herranz Castro, 64.

In Barcelona, local police said 6,000 people demonstrated, while numbers reached 30,000 in Granada and 50,000 in Seville according to authorities. Other protests took place in cities including Malaga, Palma and Valencia.

ALSO READ: Spain Socialists win Catalan separatist aid, Junts pending

After an inconclusive July 23 election, the Socialists spent weeks negotiating with smaller parties including far-left platform Sumar and Catalan, Galician and Basque nationalist parties.

The confirmed support of Junts, as well as the Basque Nationalist Party, last week, would give Sanchez an absolute majority in the 350-member lower house in a vote due to take place in the coming days.