A Spanish National Court judge on Wednesday called the head of the regional Catalan police and two pro-independence figureheads to give testimony in a probe into allegations their conduct during a protest that coincided with Spanish police raids in Barcelona aimed at thwarting a controversial separatist referendum amounted to sedition.

National court judge Carmen Lamela called on Mossos d'Esquadra Major, Josep Lluis Trapero, and the presidents of two of Catalonia's most powerful pro-independence organizations, Jordi Sánchez, of the Catalan National Assembly, and Jordi Ciuxart, head of Omnium Cultural, to appear in court on Friday, judicial sources told EFE.

The sedition probe was requested by state prosecutors following mass protests that erupted outside Catalonia's regional finance ministry on Sept. 20 as police raided the building in a bid to seize all material related to a banned referendum that on Sunday went ahead in defiance of Madrid's legal action.

Officers from Spain's militarized Civil Guard were besieged inside the ministry building and three of their police vehicles parked outside were destroyed by the large crowd of demonstrators despite the presence of the Mossos d'Esquadra.

The judge has requested a Civil Guard report on the events, including its six requests for backup lodged with the Mossos d'Esquadra, who allegedly gave scant evidence that the requests had been properly processed.

The Civil Guard reportedly told the Mossos d'Esquadra that the three vehicles contained heavy weaponry, which had the potential to drastically alter the situation should they be discovered by the protesters.

Trapero and the Catalan police came under scrutiny during the referendum amid accusations of passivity.

Furthermore, the Civil Guard said that Sánchez and Ciuxtart coordinated the demonstration but failed to use their influence over the crowd to diffuse the situation when it escalated.

In the early hours of the morning, a group of protesters attempted to push their way into the ministry and Spanish police officers inside were only able to leave after 4.00 am, some six hours after their operation had drawn to a close.

Catalan officials went ahead with the referendum on Oct. 1, despite it having been ruled unconstitutional and therefore illegal by the Spanish Constitutional Court.

National Police efforts to shut down polling stations and confiscate material, just over 2 million voters managed to cast their ballot.

Police actions caught international headlines, however, after clashes with protesters refusing to leave polling stations led to over 800 people sustaining injuries, the Catalan government said.

Regional president Carles Puigdemont announced that 92 percent of voters opted for independence.

Pro-unity voters often boycott such referendums in Catalonia as they are not sanctioned by the Spanish state.

A general strike was in place in Catalonia.

The developments prompted Spain's King Felipe VI to address the nation in a televised speech, in which he strongly condemned the actions of Catalonia's separatist leaders as a threat to Spanish unity.

On Tuesday, Puigdemont told the BBC that Catalonia, one of Spain's wealthiest regions, would unilaterally declare independence in the coming days.