Premises linked to Russian billionaire Roman Abramovich were unlawfully searched by police on Jersey, and the force has agreed to pay damages and apologise, according to a legal document.
On April 12, the Royal Court of Jersey imposed a formal freezing order on $7 billion worth of assets linked to Mr Abramovich, who made a fortune in the 1990s.
Police carried out searches of premises suspected of being connected to the billionaire.
But the legality of the search warrants issued the same day was challenged by the companies searched.
Two warrants were issued to search premises claimed to be connected to Mr Abramovich's business activities.
In a consent order dated November 9, Jersey police acknowledged that "the search warrants were obtained unlawfully" and agreed "that the search warrants should be quashed", a copy of the document, seen by Reuters, showed.
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Jersey police said the investigation was led by the Economic Crime and Confiscation Unit based in the Law Officers' Department, and that it was not appropriate to comment on "a live investigation".
The Law Officers' Department did not reply to a request for comment.
The legal document said a Jersey police officer on secondment to the Economic Crime and Confiscation Unit made the search warrant applications.
Police also agreed to pay damages and costs, and apologise to Mr Abramovich, the document said.
They confirmed that all copies of documents seized in the searches had been destroyed.
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"Mr Abramovich has always acted in accordance with the law, we are pleased that the Jersey Police have conceded in relation to these unlawful and unfounded searches," his spokeswoman said.
It was not immediately clear what effect the admission of unlawful searches would have on the $7bn freeze.
Mr Abramovich, who also holds Israeli citizenship, was one of the most powerful businessmen who earned fortunes after the 1991 break-up of the Soviet Union. Forbes has put his net worth at $8.7bn.
A commodity trader who thrived in the disorder of the 1990s under president Boris Yeltsin, he acquired stakes in the Sibneft oil company, Rusal aluminium producer and Aeroflot airline that were later sold.
Under President Vladimir Putin, Mr Abramovich served as governor of the remote Arctic region of Chukotka in Russia's Far East.
He has been involved in attempts to find a negotiated settlement to the war in Ukraine, thus far without any success.
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Britain has imposed sanctions on Mr Abramovich as a "pro-Kremlin oligarch."
"Abramovich is associated with a person who has been, and is, involved in destabilising Ukraine and undermining and threatening the territorial integrity, sovereignty and independence of Ukraine, namely President Vladimir Putin," the UK Sanctions List says.
Supporters of Mr Abramovich, who never gives interviews, say that such assertions are unproven and fail to understand the business climate of post-Soviet Russia.