A court in Jersey has frozen $7bn (£5.4bn) in assets linked to Russian billionaire Roman Abramovich.
The assets being targeted are either located in the island, or owned by Jersey-incorporated entities, the Law Offices Department of Jersey said.
Police searched addresses suspected of being connected to Mr Abramovich's business activities on Tuesday.
The island of Jersey is a well-known tax haven.
Mr Abramovich was among a number of Russian oligarchs sanctioned by the UK and the EU in response to Russia's invasion of Ukraine.
An ally of Russian President Vladimir Putin, he has assumed an unofficial role in peace talks between Ukraine and Russia.
He is best known as the owner of Premier League club Chelsea. The club is now up for sale after the British government blacklisted his finances, which were used to help fund the team's triumphs on the pitch.
Superyachts linked to the 55-year-old have also been docked in southwest Turkey, where they would not face sanctions.
Nations like Antigua and Barbuda have agreed to help Britain seize yachts owned by the businessman.