The Spanish government on Saturday said it would welcome the participation of sacked Catalan leader Carles Puigdemont in new elections.
The central government in Madrid has ordered that fresh elections for the regional parliament of Catalonia should take place in December.
It stripped Catalonia of its autonomy after the Catalan parliament voted to declare independence, the BBC reports.
Mr Puigdemont is urging "democratic opposition" to direct rule from Madrid.
He condemned the suspension of Catalonia's autonomy and promised to continue to "work to build a free country".
Spain has been gripped by a constitutional crisis since an independence referendum, organised by Mr Puigdemont's separatist government, was held earlier this month in defiance of a ruling by the Constitutional Court which had declared it illegal.
The Catalan government said that of the 43% of potential voters who took part, 90% were in favour of independence.
Friday saw the regional parliament declare independence, with Madrid responding by declaring the move illegal.
Prime Minister Mariano Rajoy then announced the dissolution of the regional parliament and the removal of Mr Puigdemont as Catalan leader, and ordered that fresh regional elections should be held.
A large anti-independence demonstration is expected to take place later on Sunday in Barcelona, Catalonia's regional capital.
The political crisis will also be played out on the football pitch in the afternoon when Real Madrid, the defending Spanish champions, travel to Catalonia to play Girona, the team supported by Mr Puigdemont.
