But the Socialists, the ruling party in Spain's national parliament, are leading in the popular vote in the Spanish region's parliamentary election, with 23.4 per cent of the ballots and 33 seats.

Even if final results confirm the outcome, it is unlikely to lead to any repeat of the chaotic, short-lived declaration of independence from Spain that took place in 2017.

Tensions have ebbed and most voters were more concerned about the coronavirus pandemic than independence.

The most likely scenario would be that the two main separatist parties extend their coalition government.

The Socialists said, however, they would try to form a government if their advantage in votes held, seeking an agreement with far-left anti-independence En Comu Podem. To do so, they would need an unlikely alliance with other parties.

"We believe change has arrived and it will stay," the Catalan Socialists top official, Eva Granados, told TV3 on Sunday.

The leftist, separatist Esquerra Republicana de Catalunya (ERC) would get 33 seats in the 135-seat assembly, and centre-right pro-independence Junts 32, based on the results to date.

Far-left separatist party CUP would get nine seats.

Far-right party Vox was set to win seats in Catalonia's regional parliament for the first time, ahead of the People's Party, the main Spanish conservative party, and the centre-right Ciudadanos. Vox is already the third-largest party in Spain's national parliament.

But with ERC seen getting more MPs than Junts this time, that could boost the stability of Spain's central government.

ERC has provided key votes to the Socialists in the Spanish parliament in exchange for talks on the Catalan political conflict.

Election monitors on Sunday swapped face masks for full personal protective equipment during the final hour of voting, which was reserved for people with confirmed or suspected COVID-19.

Australian Associated Press