Catalan pro-independence parties look set to hold on to their absolute majority in Thursday’s snap regional elections, dealing a severe blow to the Spanish government, which called the polls in the hope of heading off the secessionist threat.

With 90% of the votes counted, the three separatist parties are on course to win 70 seats in the 135-seat regional parliament even though the centre-right Citizens party appears to be the single party with the most seats.

Together for Catalonia, the party led by deposed Catalan president Carles Puigdemont, is expected to take 34 seats, the Catalan Republican Left 32 and the far-left, anti-capitalist Popular Unity Candidacy four. Between them, they will have enough seats to reassemble the parliamentary majority that put them into office after the 2015 elections.

The Citizens party, which has taken a fiercely anti-independence stance, is on track to win 36 seats, the Catalan socialist party 17, Catalunya en Comú-Podem (the Catalan version of the anti-austerity Podemos party) eight and the conservative People’s party four.

Thursday’s snap election was called in October by the Spanish prime minister, Mariano Rajoy, after he used article 155 of the constitution to take control of Catalonia and sack its government over its unilateral independence referendum and subsequent declaration of independence.

The vote, which has pitted secessionists against unionists, attracted a record turnout of 80%, dispelling fears that holding the election on a weekday rather than the usual Sunday would hit turnout appeared to have been unfounded.