KYIV - Ukrainian authorities feel newly empowered to prosecute the once-powerful tycoons known as "oligarchs" thanks to shifting political realities and the war with Russia, Kyiv's justice minister said.

Denys Maliuska spoke to Reuters in an interview on Monday as investigators probe several prominent billionaires for crimes like embezzlement, fraud and money laundering in cases mostly opened during the 20-month-old Russian invasion.

"Everyone was afraid of (the) consequences of indicting oligarchs, but this is no longer the case," he said.

Ukraine had long struggled to shake off the influence of its shadowy tycoons, who used the huge industrial wealth they amassed after the 1991 collapse of the Soviet Union to gain political influence and power.

But Russia's invasion has eaten into their influence, destroying industrial assets in the east and south, while the television channels they controlled have been broadcasting under a centralised signal since Moscow's February 2022 attack.

A 2021 law aimed at curbing their political and economic influence also sent a clear signal, Maliuska said, and now oligarchs have become "quite accessible" to authorities.

"It's easier to get access to documents, to witnesses, to case files, which was impossible even a couple of years ago for law enforcement agencies to achieve," he said.

Billionaire Ihor Kolomoisky, once considered President Volodymyr Zelenskiy's chief patron, was jailed last month and is suspected of fraud and money laundering.

In May, Ukraine also announced it suspected businessman Dmytro Firtash, who is wanted by the United States, and companies under his control of stealing up to $485 million in a "large-scale scheme" involving Ukraine's gas transit system.

Both have denied wrongdoing.

Authorities earlier this year also seized more than $375 million worth of assets they said belonged to exiled billionaire Vadym Novynskyi, whom they allege aided Russia. He denies wrongdoing.

The Ukrainian investment group Smart Holding said the assets no longer belonged to Novynskyi, whom it said gave up ownership last year.

Ukraine wants to join the European Union and show its Western partners that it can handle a huge influx of investment and funds to help rebuild the country.

Anti-corruption agencies have launched cases against current and former officials, while authorities are also hoping to overhaul the judiciary and cement the rule of law.

The EU has recommended that Kyiv defer the implementation of the 2021 legislation, which places those designated by the National Security Council as oligarchs in a register, because of its potential to be "misused for political purposes".

Maliuska said that Kyiv would comply with the EU's recommendations but that Ukrainian law enforcement, in the meantime, would continue their investigations, which he called "game-changers" for Kyiv's bid to clean up.

(Reporting by Dan Peleschuk, Editing by Tom Balmforth and Mark Potter )