Former Chelsea owner Mr Abramovich and Mr Usmanov, who also had a stake in Everton FC, were both sanctioned in March 2022 following the Russian invasion of Ukraine the month before as they are said to have close ties to Vladimir Putin and the Kremlin - which Mr Abramovich denies.

Oligarchs had more than £18bn in assets frozen in the UK due to the initial sanctions.

But many were still able to operate in the UK through financial fixers, family members, offshore trusts and shell companies.

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More than a year since those initial sanctions were imposed the government has now identified and sanctioned several people who were helping oligarchs continue to do business in the UK.

On Wednesday, the US also imposed further sanctions on Russian financial facilitators and sanctions evaders around the world, including Mr Usmanov's company, USM Holdings and its entities.

One of the entities is Megafon, one of Russia's big four telecoms operators, marking a shift as so far Western sanctions have stopped short of targeting Russia's telecoms infrastructure.

As part of the UK sanctions, two Cypriots working for Mr Abramovich and Mr Usmanov are the key pair affected by the new measures.

The Foreign Office said corporate services provider Demetris Ioannides is responsible for "crafting the murky offshore structures" used to hide more than £760m of Mr Abramovich's assets before the oligarch was sanctioned last year.

While lawyer Christodoulos Vassiliades is "at the centre of a web of trusts and offshore companies" linking Mr Usmanov and the Sutton Place Estate, the Tudor manor house owned by the Russian near Guildford, Surrey, previously owned by J Paul Getty.

Mr Usmanov's financial network has also been sanctioned, including Curzon Square Limited, the company that acted as his London office and leaseholder of a 72-room Grade II-listed mansion in Mayfair's Curzon Square, a short walk from Buckingham Palace.

He transferred Curzon Square Ltd's stake in the mansion to his business empire, Russia's largest iron ore producer Metalloinvest, just three days before the invasion of Ukraine.

As the sanctions were only initially placed on him, Curzon Square Ltd was free to control property interests in London.

USM, the company that Mr Usmanov has major shares in and owns Metalloinvest, is also included in the new measures.

Hanley Limited, an Isle of Man-based company - through which Mr Usmanov bought Grade II listed Beechwood House in Hampstead, north London for £48m in 2008 - has also now been sanctioned.

The father and daughter of Mr Usmanov's business partner Andrei Skoch - Vladimir and Varvara Skoch - were sanctioned, too.

'We are closing the net on the Russian elite'

Foreign Secretary James Cleverly said: "We are closing the net on the Russian elite and those who try to help them hide their money for war.

"There's no place to hide. We will keep cutting them off from assets they thought were successfully hidden.

"Together with our international partners the UK will continue to crack down on those who are supporting the war. We won't stop until Putin does."

Family members of other sanctioned oligarchs, who the government says are being used as proxies to hide their assets, are the others who have been sanctioned in the latest round of measures.

They include the daughter, son and wife of Vladimir Evtushankov, the billionaire majority owner and founder of Russian conglomerate Sistema, which specialises in banking and hotels, and formerly aerospace and defence.

Gulnara Kerimova, daughter of billionaire oligarch and Russian politician Suleyman Kerimov, a major stakeholder in Gazprom, Uralkali and Sberbank, has been sanctioned as she holds four luxury villas in France on behalf of her father.

Mr Kerimov's nephew, Nariman Gadzhiev, is also on the list as he acts as a beneficiary owner of a series of shell companies connected to his uncle, including one that transferred hundreds of millions of dollars to companies linked to Mr Kerimov.

Oksana Marchenko, the wife of key Putin ally and former Ukrainian politician Victor Medvedchuk, and the owner of multiple luxury properties in Crimea, finishes off the new list of sanctioned individuals.