Protesters on Monday seized a mansion linked to the sanctioned Russian oligarch Oleg Deripaska in one of central London's most exclusive addresses.
Banners were unfurled from the property at 5 Belgrave Square, including one stating "This property has been liberated", alongside the Ukrainian flag.
Police, who were called out in the early hours, set up a cordon before later using a drill to break open the front door to gain entry and used a crane to access the balcony.
One of those inside told AFP by telephone: "We are a property liberation front. That's what we do. It's not really squatting, it's liberating."
Another said: "Our intention is to use it to house (Ukrainian) refugees."
The activists criticised the length of time it may take to implement UK sanctions against those identified by the government as being part of Russian President Vladimir Putin's inner circle.
"They say it might take up to six months to seize their property. Come on, it's ridiculous," one said.
Deripaska is not listed on UK Land Registry records as the owner of the property in the upmarket Belgravia area, near Hyde Park and Queen Elizabeth II's Buckingham Palace.
Instead, the owners are listed as Ravellot Limited, based in the British Virgin Islands, managed by Graham Bonham Carter at the same address and a nearby property.
In 2007, a High Court judgement said Deripaska "beneficially owns" a house at 5 Belgrave Square, London.
On March 4, the UK's National Crime Agency said it had secured two account-freezing orders in respect of five bank accounts held by Bonham Carter, a British businessman.
"The orders were obtained on the basis that there are reasonable grounds to suspect that the money in the accounts was derived from the laundering of funds of an individual subject to sanctions in the United States, namely Oleg Deripaska," it added in a statement.
"The accounts contain funds of a value totalling approximately £110,000 ($144,000, 131,000 euros)."
Deripaska was last week hit with an assets freeze and travel ban alongside six other Russian billionaires, including his former business associate Roman Abramovich.
The US Treasury designated him in 2018 as part of moves against a number of Russian oligarchs and the companies they own or control, Russian officials and businesses.
Two men in France were in custody on Monday after they broke into a villa owned by Putin's former son-in-law and unfurled a Ukrainian flag in the southern French city of Biarritz.