After President Vladimir Putin ordered tens of thousands of troops into Ukraine on Feb. 24, the EU slapped sanctions on Russian officials and a host of Russian businessmen while freezing hundreds of billions of dollars of Russian assets.

The EU in March 2022 described Abramovich, now 56, as an "oligarch who has close ties to Vladimir Putin" including "privileged access" to the Kremlin chief, connections the EU said had helped him maintain his assets.

Abramovich filed a challenge to the EU sanctions on May 25, 2022, and on Thursday the General Court of the Court of Justice of the European Union will hear the challenge, a source with knowledge of the matter told Reuters.

His lawyers will argue that the EU sanctions are baseless and were imposed purely because he is a famous Russian businessman, the source said.

"He was not sanctioned because of evidence relating to the criteria: he was sanctioned simply because politically, the most famous Russian businessman had to be even if this is a manifest error," the source said.

Abramovich, who also holds Israeli citizenship, was one of the most powerful businessmen who earned fabulous fortunes after the 1991 break-up of the Soviet Union. Forbes has put his net worth at $9.2 billion.

(Reporting by Guy Faulconbridge; Editing by Andrew Osborn)