A leading rabbi who helped Russian billionaire Roman Abramovich obtain his Portuguese citizenship has been told he cannot leave Portugal and must present himself to authorities when required.

Daniel Litvak was detained on 10 March in widely media reported coverage saying that this formed part of an investigation into how citizenship had been granted.

On 11 March, Abramovich was sanctioned by the UK in response to Russia's invasion of Ukraine.

He is one of seven oligarchs to be hit with fresh sanctions, including asset freezes and travel bans.

The Premier League has disqualified him as a director of the club.

International Investment published an article on 20 January this year about how Abramovich had accessed low tax citizenship by lineage.

Portuguese citizenship gave him access to all EU and EEC member states under the Treaty of Rome's "Four Freedoms".

Along with his Israeli passport, his new Portuguese passport also gave him visa-free travel to the UK.

Abramovich was granted Portuguese citizenship in April 2021 under a law that offered naturalisation to descendants of Sephardic Jews, who were expelled from the Iberian peninsula more than 400 years ago during the Inquisition.

Applicants for Portuguese citizenship via this route are assessed by experts at one of Portugal's Jewish communities in either Lisbon or Porto. Mr Litvak is the rabbi for the community in Porto (northern Portugal) and was responsible for assessing Mr Abramovich's application.

Litvak was detained by authorities as he was preparing to travel to Israel. He was asked to hand over his passport and will have to periodically present himself to authorities.

Portugal's Judicial Police and public prosecutor said on 11 March that there were suspicions of money laundering, corruption, fraud and falsification of documents in the process of granting citizenship to descendants of Sephardic Jews.

Porto's Jewish community has denied any wrongdoing and said it was the target of a smear campaign, according to the BBC in its report on this story.

They added that Litvak oversaw the department that grants certification of an individual's Sephardic Jewish heritage and the criteria used for granting someone Portuguese nationality had "been accepted by successive governments".