The EU's General Court, the first instance at the Luxembourg-based Court of Justice of the EU (CJEU), also threw out similar appeals by Timchenko's wife, Elena, as well as Russian businessman Dmitry Pumpyansky and his wife Galina.

The rulings can be appealed to the CJEU's highest instance.

Gennady Timchenko resigned from management of Russia's largest private natural gas producer Novatek last year in March after being targeted with the sanctions by the 27-nation EU.

The EU also banned Dmitry Pumpyansky, saying he is a billionaire whose businesses support and benefit from working with the Russian state.

Two more men - Tigran Khudaverdyan, a former head of Yandex, Russia's answer to Google, and Alexander Shulgin, a former head of Russia's e-commerce platform Ozon - also lost their appeals against EU sanctions at the bloc's General Court on Wednesday.

The EU has imposed multiple rounds of sanctions since Russia invaded Ukraine last year. They include trade restrictions to cut defence and other exports to Russia, as well as restrictions on Russia's banking sector, among others.

The individual sanctions, like those challenged by Timchenko, cover a travel ban and a freeze of all assets held in the EU. The list encompasses nearly 1,800 people and entities with an estimated 21.5 billion euros worth of holdings affected.

The bloc is discussing whether and how to use these holdings - including its share of the further 300 billion euros worth of Russian central bank assets frozen in the EU and G7 countries - to help finance rebuilding Ukraine from the war.

Nearly 80 challenges to EU sanctions over the war in Ukraine had been filed at the CJEU, according to information from the court last March, the latest available.

Before the Wednesday rulings, the court has already dismissed a challenge by Russian state-owned television Russia Today against a broadcasting ban in the EU.

The mother of Russia's late mercenary boss Yevgeny Prigozhin scored a rare victory against the sanctions, though the ruling last March had no immediate practical effect as she remained sanctioned under separate decisions.

Russian billionaire Roman Abramovich is challenging EU sanctions as well, a source familiar with the matter said in July.

(Additional reporting by Benoit Van Overstraeten; writing by Gabriela Baczynska; editing by Mark Heinrich)

By Gabriela Baczynska