A sanctioned Russian billionaire says the UK searched his multimillion-dollar London home illegally using allegations from a 15-year-old report

• Russian billionaire Mikhail Fridman said a UK police warrant to search his home was unlawfully obtained, per Reuters.
• He wants to overturn the warrant which he said was obtained based on allegations from a 2007 report.

Sanctioned Russian oligarch Mikhail Fridman told London's High Court on Thursday that a UK police raid on his mansion in London was illegal and based on allegations from a 15-year-old report, according to a Reuters report.

Fridman's lawyers argued that the warrant to search his home was unlawfully obtained and are now seeking to overturn it, per Reuters.

Back in December, the UK National Crime Agency, or NCA, searched Fridman's multi-million dollar home over several allegations — including conspiracy to evade UK sanctions and money laundering — per Reuters.

Fridman, who is worth $12.2 billion as of Thursday, has been sanctioned by the UK and the European Union after Russia invaded Ukraine.

Lawyers for the 59-year-old Russian businessman, who was born in Ukraine, said the accusations of wrongdoing were "gratuitous and unjustified slurs against a businessman of good character," the news agency reported.

Fridman is the founder and largest shareholder of the Alfa Group, which includes Russia's largest bank. He moved to London in 2013.

Hugo Keith, the billionaire's lawyer, said in court filings that the allegations — from a 2007 report republished by WikiLeaks in 2012 — "absolutely typical of classic kompromat, damaging and untrue information assembled and used to create negative publicity and to exert influence over the subject," per Reuters.

"Kompromat" refers to compromising information that is used to blackmail or discredit a person or group, typically for political purposes," according to the Merriam-Webster Dictionary.

Cathryn McGahey, the NCA's lawyer, said in court filings the UK government agency admitted its raid on Fridman's house was "unlawful," per Reuters.

Keith said the NCA has already dropped its inquiry into the alleged conspiracies to defraud and commit perjury, according to the news agency.

An NCA spokesperson told Insider that it accepted that the search warrant contained technical errors. However, "the Agency acted in good faith and we will continue to consider the facts relating to this case."

Fridman's legal representatives did not immediately respond to requests for comment from Insider sent outside regular business hours.