Washington DC - The Biden administration has imposed fresh economic sanctions on pro-Kremlin oligarchs and on Russian President Vladimir Putin's purported girlfriend.

"As innocent people suffer from Russia’s illegal war of aggression, Putin’s allies have enriched themselves and funded opulent lifestyles," said Treasury Secretary Janet Yellen on Tuesday.

"The Treasury Department will use every tool at our disposal to make sure that Russian elites and the Kremlin’s enablers are held accountable for their complicity in a war that has cost countless lives. Together with our allies, the United States will also continue to choke off revenue and equipment underpinning Russia’s unprovoked war in Ukraine," she added.

Sanctions set by the US State Department in tandem with the Treasury "impose severe costs for those who support President Vladimir Putin’s war," the Department of the Treasury said in a statement.

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Following a similar move by the European Union, the US sanctioned former gymnast Alina Kabaeva.

The 2004 Olympic champion now runs the large Russian media company NMG. The EU said the company was "in close contact" with President Vladimir Putin. Press reports have linked Kabaeva with Putin.

In April, the US sanctioned Putin's two adult daughters.

Putin's confidant Andrey Guryev and his son are also affected by the latest sanctions. The luxury yacht Alfa Nero, which Guryev is said to have bought in 2014 for $120 million, was mentioned by name.