A rabbi responsible for the certification that allowed Russian billionaire Roman Abramovich and others to obtain Portuguese citizenship is not allowed to leave the country and must present himself to authorities when required, Lusa news agency said on Saturday.
Officers of the Judicial Police, the national criminal investigation agency, detained rabbi Daniel Litvak on Thursday as part of an ongoing public prosecutors inquiry into how Chelsea soccer club owner Abramovich was granted citizenship.
Abramovich has been sanctioned by the British government over his links to Russian President Vladimir Putin and Russia's invasion of Ukraine. He has denied having such ties.
He was granted Portuguese citizenship last year based on a law offering naturalisation to descendants of Sephardic Jews who were expelled from the Iberian peninsula during the Mediaeval Inquisition.
Applicants' genealogies are vetted by experts at one of Portugal's Jewish communities in Lisbon or Porto. The Porto community, where Litvak is the rabbi, was responsible for Abramovich's process.
There is little known history of Sephardic Jews in Russia, although Abramovich is a common surname of Ashkenazi Jewish origin.
Citing a judiciary source, Lusa said authorities took "coercive measures" against Litvak while he waits for legal proceedings to move forward.
The Judicial Police did not immediately reply to a Reuters request for comment.
Representatives of the Jewish community in Porto did not immediately respond to requests for comment.
Lusa said Litvak, who was preparing to travel to Israel when he was detained, was asked to hand over his passport and must periodically present himself to authorities.
Porto's Jewish community has denied any wrongdoing and said it was the target of a smear campaign, adding that Litvak oversaw the department that certifies Portuguese nationality on the basis of criteria that "have been accepted by successive governments".
In a statement on Friday, the Judicial Police and the public prosecutor said there were suspicions of money laundering, corruption, fraud and falsification of documents in the process of granting citizenship to descendants of Sephardic Jews.
Close to 57,000 descendants of Sephardic Jews have been granted citizenship since the law was implemented in 2015, according to official data.