Vladimir Kokorev, aged 63, and his son Igor have been imprisoned on the Canary Islands without charge for two years.
Kokorev’s wife Yulia, 68, was released on bail on similar charges earlier this week.
They face “trumped up” charges of alleged money laundering but have strenuously denied any wrongdoing.
Lawyers and others who are championing their case appeared at a news conference in the European Parliament on 28 September where they appealed to the EU to intervene in what was described as “blatant contravention” of European standards.
The call for an investigation is spearheaded by Italian centre right MEP Fulvio Martusciello who told reporters the case gave “cause for real concern.”
As Kokorev is of Russian-Jewish origin, the MEP also said there were undertones of “anti-Semitism” and “xenophobia” to the case.
Kokorev, a wealthy Spanish entrepreneur was arrested in Panama where he lived in September 2015, along with his wife and 35-year-old son in connection with an alleged money laundering scheme on behalf of the President of Equatorial Guinea.
The family agreed to extradition to Spain where they were jailed on the orders of Spanish investigative judge Ana Isabel de Vega Serrano.
They have remained in pre-trial detention for two years without formal charges being laid or a date set for their trial.
In August, the same judge ordered that their imprisonment continue for another two years, citing “complexities” of the case and the ongoing investigation.
All three deny any wrongdoing with Kokorev insisting that his business dealings with Equatorial Guinea are legal and legitimate.
Spanish lawyer Alvaro Campanero accused the judge of an “unprecedented abuse of power” and pointed out that the original charges had been altered without reason from money laundering to gaining from the proceeds of illegal weapon trafficking.

Another member of Kokorev’s legal team, Antonio Cabrera, told Brussels-based journalists that the case highlighted “serious shortcomings” in the Spanish legal system.
As Spain is a member of the EU and party to its conventions, he said it was “beholden” on the EU to intervene.
He also pointed out that Spain had recently adopted new legislation which stated that no-one should be held more than two years in custody without being charged or brought to trial.
Cabrera said: “There have been serious contraventions of European legal standards in this case and the EU needs to be made aware of this.
“That is why we have come to the European parliament to ask MEPs and others to ask what is going on with this case.”
He said that in the first instance the EU should press Spanish appeal judges to move the case from Las Palmas where the two men are currently held to a “correct court’ in Madrid where, he said, the Kokorev family might expect to receive “fairer treatment.”
Up to 60 documents in the possession of Kokorev’s legal team “clearly demonstrate” that he was innocent of any illegal activity, it was said.
Publicity over the event in Parliament may, he said, have led to the decision this week to release Kokorev’s wife from custody.
Further comment came from Carmelo Nvono Nca, the ambassador for Equatorial Guinea to the EU, who welcomed the news conference as an opportunity to highlight the alleged injustice suffered by the Kokorevs.
Another speaker, Inna Stolarewicz, travelled from her home in Israel to speak on behalf of Kokorev, who is her uncle.
She said he was in poor health but had been denied access to professional medical help.
“Igor, during his imprisonment, has become a father but, thus far, has been unable to see his young daughter,” she said.
Justino Obama Nve, a personal friend of Kokorev, said he believed there was “nothing illegal” in the shipment contracts which had existed between Kokorev and Equatorial Guinea.
MEP Martusciello, who chairs the Parliament’s delegation to Israel, said he would raise the case during an upcoming plenary session of the assembly.
He said: “It is not for us to decide if Mr Kokorev is guilty or innocent of the charges against him, that is for a court to decide. But what should concern us all is the fact that he, his wife and son are being denied justice and due process of law.”
The MEP, who hosted the event, added: “Two years in detention without specific charges with the prospect of a further two years for no good reason is an affront to all that we Europeans believe in. For his wife and son to be also imprisoned without charge for no good reason is totally unacceptable.”
He said he would take a “special interest” in the matter and will call for an independent inquiry.
“The treatment of Vladimir Kokorev is shameful, anti-Semitic and an affront to the basic values of the EU.”

eureporter.co