BARCELONA, Spain (AP) — A judge in Barcelona is probing possible links between some of the promoters of Catalonia’s 2017 attempt to declare independence from the rest of Spain with an alleged misinformation campaign and overall effort to destabilize Europe that Spanish investigators link to Russia.

The probe authorized by judge Joaquín Aguirre led on Wednesday to the arrest of 21 suspects on suspicions of corruption and promoting public disorder. Aguirre partly based the probe on police evidence that purported Russian agents allegedly offered to provide military aid to Catalan separatists at the height of their failed secession bid in 2017.

On the recording, one of the detainees mentions an offer by the alleged Russian agents to provide former Catalan president Carles Puigdemont with 10,000 soldiers, apparently to help in a theoretical armed conflict with Spanish authorities. The court document provided no indication that the offer was ever considered by Puigdemont, nor does it provide additional evidence that the offer was even genuine, or feasible.

The Catalan separatist movement has always proclaimed non-violent beliefs, even though last year there were violent clashes with police after several top leaders were sentenced to prison for their roles in the 2017 breakaway bid.

Besides the putative military aid, the probe also targets the alleged misuse of public funds for the separatist movement in Spain as well as the allegedly active role of Russian-backed disinformation campaigns to discredit Spain.

“Russian interference as a geopolitical strategy was a fact during the fall of 2017 when (the Russians) spread fake news and disinformation," the judge said, citing online items backing the Catalan separatists spread by Russian news platforms.

The Spanish government had accused Russia in 2017 of meddling in the Catalan conflict, a charge that Russian officials denied then.

There was no immediate reaction from Russian officials Wednesday about the probe authorized by Aguirre.

Spain’s interior ministry said the individuals arrested on Wednesday were being investigated for alleged embezzlement and money laundering. Investigations revealed that money intended for Barcelona’s provincial government and a regional entity for promoting sports teams had been diverted illegally, the ministry said.

Josep Lluís Alay, a close collaborator of Puigdemont who runs an office of the ex-leader in Barcelona, was one of the detained. Others included David Madi and Oriol Vendrell, two former politicians for Catalonia's major separatist parties.

Puigdemont said on Twitter that Alay and the others “must be immediately release(d). Acting against political dissidents is a huge violation of fundamental rights.”

After the breakaway bid collapsed, Puigdemont fled Spain to Brussels, where he has campaigned to raise support for his cause internationally. Puigdemont is currently a European Parliament member.

Another detainee, Oriol Soler, is a publisher who is considered one of the top strategists of the separatist movement. He is being investigated for allegedly meeting with Wikileaks founder Julian Assange and with Russian contacts to promote the separatist cause and discredit Spain internationally.

The court document said the alleged meeting between Soler and Assange in Sept. 2017 “falls within the strategy of misinformation and destabilization in which the Kremlin has also participated as part of its general narrative that the European Union is on the brink of collapse, the principal message of the news outlets controlled by the Kremlin.”

Soler’s defense attorney, Benet Salellas, said that his client is innocent and “denounces that the justice system is being utilized to fight against the Catalan independence movement.”

The arrests sparked several small protests across Catalonia.

Catalonia's independence movement is supported by roughly half the population of wealth region but rejected by the other half and across Spain as a whole.

Spain’s Constitution deems the nation indivisible.

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AP writers Aritz Parra and Ciaran Giles contributed from Madrid.