KYIV -- The Security Service of Ukraine (SBU) has frozen more assets of Oksana Marchenko, the wife of pro-Russian politician Viktor Medvedchuk.

The SBU said on June 2 that the assets, estimated to have a value of 740 million hryvnyas ($19.8 million), are related to stakes Marchenko owned via offshore schemes in several energy transportation companies located in Ukraine's Black Sea port city of Odesa -- Eximnaftoprodukt, Sintez Oil, Sintez Transit, Ukrloadsystem, Odesnaftoprodukt, Black Sea Fuel Terminal, and Albion Commodities.

"The freezing of these assets will prevent their re-registration under other fake names and will allow them to be transferred for our state's needs," the SBU statement said.

Marchenko's husband, Viktor Medvedchuk, is a longtime Ukrainian political fixture and reportedly a godfather to Russian President Vladimir Putin's daughter. Medvedchuk was one of Ukraine’s wealthiest individuals with a fortune estimated in the hundreds of millions of dollars, including energy assets in Russia.

Ukrainian courts have already frozen and impounded assets and property in Ukraine held by Marchenko with an estimated value of 7 billion hryvnyas ($188 million).

In April, Ukraine's Interior Ministry added Marchenko, who is not in Ukraine, to its wanted list, saying she is suspected of financing actions to forcibly disrupt Ukraine's constitutional order, seize power, and change the state borders of Ukraine.

Ukraine sanctioned Medvedchuk in February 2021, freezing his assets, and took off the air three television stations it said belonged to him for promoting Russian propaganda.

He was arrested in 2021 on charges of treason and terrorism financing and later placed under house arrest on bail.

Shortly after Russia launched its invasion of Ukraine in late February last year, Medvedchuk escaped house arrest, but he was rearrested in April while trying to flee to Russia.

In June, a court in Ukraine banned the Medvedchuk-led pro-Russia Opposition Platform -- For Life political party.

In September, Ukrainian authorities handed the 68-year-old politician over to Russia in a prisoner exchange.

Ukrainian President Volodymyr Zelenskiy has since stripped Medvedchuk and three other pro-Russian Ukrainian politicians of their Ukrainian citizenship.