Tens of thousands took to the streets of the Basque Country’s largest city of Bilbao despite the rain to express their discontent with Madrid’s decision to impose direct rule over Catalonia following its unilateral declaration of independence.

The streets of Bilbao were flooded with protesters carrying umbrellas on Saturday. Some 44,000 demonstrators took part in the rally, according to local media. The local authorities put the number of participants at 35,000.

The protesters were rallying against what they called the “involution” of the Spanish state and “repressive” measures taken against the Catalan government, as well as against the violation of Catalonia’s right to self-rule. They were waving the flags of the Basque Country, as well as those of Catalonia.

The demonstrators were carrying a large banner that read: “Against Article 155, [for] Democracy and the right to decide.” Article 155 of the Spanish constitution was used by the central government to remove the Catalan government from power and impose direct rule over the rebellious region.

The march was organized by Basque pro-independence groups and local labor unions, as well as by the regional office of the leftist Spanish Podemos Party. However, the ruling Basque Nationalist Party distanced itself from the rally, even though it has previously criticized Madrid’s actions taken against the Catalan government.

The Basque Country has long been one of Spain’s most troubled regions as its violent separatist group, ETA, waged an armed struggle for an independent Basque state in northern Spain and southwestern France for four decades. The troubles claimed the lives of more than 850 people, including state officials, police officers and civilians.

READ MORE: Terrorist group ETA disarms after 40yr fight for independent state that killed 850+

ETA called a ceasefire in 2011 and eventually disarmed in April 2017. Now, the former ETA members call for opposition to Madrid. "Now that we are in this situation, it is necessary that the Basques take to the streets and build a popular democratic wall to help us confront it," said Arnaldo Otegi, the leader of Basque pro-independence party EH Bildu and a former jailed ETA member.

A day before the rally, on Friday, a Spanish judge issued a European arrest warrant for the deposed Catalan President Carles Puigdemont. On Sunday, Puigdemont and four Catalan ex-ministers turned themselves in to police in Belgium, where they fled after Madrid imposed direct rule over Catalonia.

READ MORE: Ex-Catalan leader Puigdemont & 4 ex-ministers turn themselves in to Belgian police – prosecutor

The Spanish government suspended Catalan autonomy on October 27 in response to the regional parliament declaring independence earlier the same day. Almost a month earlier, the region overwhelmingly voted to break away from Spain, although fewer than 50 percent of those eligible to vote took part in the plebiscite.

In the meantime, the Catalan population remains split over the issue of independence, recent polls show. The regional capital, Barcelona, saw massive rallies held both in support and against the breakaway from Spain.