Russian oligarch Roman Abramovich, the outgoing owner of Chelsea FC and a longtime ally of President Vladimir Putin, has been sanctioned by U.K. authorities.

 UK adds Russian billionaire and Chelsea soccer club owner Roman Abramovich to sanctions list

Roman Abramovich, owner of Chelsea smiles .

The British government said Thursday that Abramovich was among seven Russian businessmen added to its sanctions list as it ramps up pressure on the pariah state over its invasion of Ukraine.

The new list includes further members of Putin's inner circle, such as Oleg Deripaska, Dmitri Lebedev and Igor Sechin, who have a combined net worth of over £15 billion ($19.7 billion), according to a government announcement.

All seven men will see their assets frozen and travel restricted.

"There can be no safe havens for those who have supported Putin's vicious assault on Ukraine," British Prime Minister Boris Johnson said.

The crackdown follows Ambramovich's announcement last week that he would sell his prized Chelsea soccer club, alongside a string of luxury London properties, as he embarked on a fire sale of his U.K. assets.

The 55-year-old, whose wealth originally derives from the privatization of Russian industry, said at the time that the sale was in the "best interest of the club," and that all net proceeds from the sale would be donated to victims of the war.

Following the sanctions announcement, the prospective takeover of Chelsea is now on hold and the government must grant permission for any sale to go through.

The U.K. sports ministry said it would work closely with the club and wider football league to ensure matches could continue being played.

"The license will be kept under constant review and we will work closely with the football authorities," a government spokesperson said.

A spokesperson for Ambramovich said she could not immediately comment.

Going after the Russian oligarchs

There have been growing calls from British lawmakers to target Abramovich, who until now had avoided the sanctions faced by some of his peers — even as he publicly shed several of his most valuable ties to the U.K.

Johnson said Thursday's move demonstrated the government's commitment to pressuring those with ties to the Kremlin as the bloody war enters its second week.

"Today's sanctions are the latest step in the U.K.'s unwavering support for the Ukrainian people. We will be ruthless in pursuing those who enable the killing of civilians, destruction of hospitals and illegal occupation of sovereign allies," he said.

Among the other men sanctioned were Deripaska, who has stakes in En+ Group, Lebedev, chairman of Bank Rossiya, and Sechin, chief executive of Russian oil group Rosneft.

Alexey Miller, chief executive of energy company Gazprom, and Nikolai Tokarev, president of the Russia state-owned pipeline company Transneft, were also hit.

The sanctions come ahead of a new so-called economic crime bill, set to be written into British law later this month, which will increase the speed and severity with which the government can clampdown on criminals.

It says the bill will also stop wealthy Russians using London for money laundering purposes and hiding gains linked to organized crime.