Spain’s hard-Right has warned of a “permanent coup” in Catalonia as nationalists looks set to make big gains in Sunday’s general election following weeks of sometimes violent protests.

As Spanish voters head to the polls for the fourth time in four years - and the second time in 2019 - the populist Vox party looks set to make the largest gains from fears that separatist Catalan movement is running out of control.

"There's a permanent coup d'etat in Catalonia," said the Vox leader Santiago Abascal in a pre-election television debate on Monday night, arguing that the conservative Popular Party and the Socialists, which have dominated Spanish politics for decades, were both equally to blame.

Mr Abascal said a Vox government would impose direct rule over Catalonia and order the arrest of the region’s president, Quim Torra, who has promised to continue a drive for independence.

Right-wing parties are now competing on which would take a harder line on the Catalonia issue hoping to attract more votes on Sunday.

Opinion polls show that Vox - which only won its first seats in Spain’s national parliament at last April’s general election - is now on target to become Spain’s third-biggest party with some 45 seats, up from 24 in the previous ballot.