Ukrainian President Volodymyr Zelenskyy on Thursday signed a decree imposing sanctions against two individuals reportedly involved in an ongoing $100 million corruption probe into the country’s energy sector.

Published on the website of Ukraine’s presidency, the decree imposed sanctions on Timur Mindich, a businessman and co-owner of the Kvartal 95 production company, and Oleksandr Tsukerman, both of whom are reported to be involved in an energy corruption probe launched by Ukraine’s anti-corruption agencies earlier this week.

Zelenskyy is one of three individuals who founded the production company based in the Ukrainian capital of Kyiv in 2003.

The decree was signed a day after Energy Minister Svitlana Hrynchuk and Justice Minister Herman Halushchenko submitted letters of resignation, according to Prime Minister Yulia Svyrydenko, who also declared suspending the deputy head of national nuclear energy provider Energoatom from his post.

The two ministers submitted their resignations after Zelenskyy called on Svyrydenko in an evening video address to ensure both ministers did so, arguing they “cannot remain in office” amid the ongoing probe.

“I will sign a decree to impose sanctions on two individuals implicated in the NABU case concerning Energoatom,” he added. Both Mindich and Tsukerman are noted in the presidential decree as Israeli citizens.

On Monday, Ukraine launched a “large-scale operation” into the country’s energy sector to uncover graft involving what its National Anti-Corruption Bureau (NABU) described as a “high-level criminal organization” seeking to influence strategic state enterprises, particularly Energoatom.

NABU said its investigation involved 15 months of work and 1,000 hours of audio recordings, and that members of the “criminal organization” allegedly demanded illegal benefits to the tune of 10%-15% of a state contract value.

“Using official connections in the (energy) ministry and the state-owned company, they ensured control over personnel decisions, procurement processes, and the movement of financial flows,” the bureau went on to say, adding that about $100 million had passed through the scheme.

It was noted a day later that five people were detained and seven others had been notified of suspicion, including a businessman who led the organization and a former advisor to Ukraine’s energy minister, while over 70 searches were conducted.

On the day of the investigation’s launch, Ukraine’s state news agency, Ukrinform, citing a source, reported that Mindich and Halushchenko’s homes were searched as part of the probe.

Meanwhile, an article by the Ukrainska Pravda newspaper on Wednesday reported that Mindich left the country for Poland over four hours before his home was searched. The State Border Service confirmed on the same day that Mindich legally crossed the country’s border into neighboring Poland.

The investigation comes just four months after Zelenskyy reinstated the independence of the country’s two major anti-corruption agencies.

Zelenskyy had signed measures into law that brought NABU and the Specialized Anti-Corruption Prosecutor’s Office (SAPO) under the oversight of the prosecutor general. He reversed the measures, however, after major protests, including in the capital, Kyiv.

A crackdown on corruption is critical if Ukraine hopes to advance its application to join the 27-member European Union, which formally opened accession negotiations with Kyiv in June 2024.

Critics say Kyiv has long suffered from widespread corruption, and the ongoing war with Russia is said to have overshadowed efforts to stamp out graft.