Ukrainian President Volodymyr Zelenskyy is grappling with the fallout from allegations in a major corruption scandal that has engulfed his administration, while European Union officials warned that Ukraine must crack down on graft but offered assurances that the flow of financial aid won’t stop as Kyiv strains to hold back Russia’s invasion.

German Chancellor Friedrich Merz stressed European concerns about corruption in Ukraine when he spoke by phone with Zelenskyy on Thursday.

Merz “underlined the German government’s expectation that Ukraine press ahead energetically with fighting corruption and further reforms, particularly in the area of the rule of law,” Merz’s office said in a statement.

Zelenskyy, the statement said, promised “full transparency, long-term support for the independent anti-corruption authorities and quick further measures in order to win back the confidence of the Ukrainian population, European partners and international donors.”

At the same time, a European Commission spokesperson said that uncovering the alleged kickback scheme demonstrated that Ukraine’s efforts to fight corruption are working as the country strives to meet the standards for EU membership.

“This investigation shows that anti-corruption bodies are in place and functioning in Ukraine,” Guillaume Mercier said in Brussels.

“Let me stress that the fight against corruption is key for a country to join the EU. It requires continuous efforts to guarantee a strong capacity to combat corruption and a respect for the rule of law.”

After Zelenskyy’s justice and energy ministers quit Wednesday amid the investigation into alleged energy sector graft, the government fired the vice president of Energoatom, the state-owned nuclear power company believed by investigators to be at the center of the kickback scheme.

The EU and other foreign partners have poured money into Ukraine’s energy sector. Russia has relentlessly bombarded the power grid, which requires repeated repairs.

The heads of Energoatom’s finance, legal and procurement departments and a consultant to Energoatom’s president were also dismissed in the clear-out, Prime Minister Yuliia Svyrydenko said late Wednesday.

“During the full-scale war, when the enemy is destroying our energy infrastructure every day and the country is living under power outage schedules, any form of corruption is unacceptable,” Svyrydenko said in a video statement Thursday.

“In the most difficult times, our strength lies in unity. Eradicating corruption is a matter of honor and dignity,” she said.

A Kyiv court has begun hearing evidence from anti-corruption watchdogs whose 15-month investigation, including 1,000 hours of wiretaps, has brought the detention of five people and implicated another seven in the scheme that allegedly earned about $100 million.

Tymur Mindich, a co-owner of Zelenskyy’s Kvartal 95 media production company, is the conspiracy’s suspected mastermind. His whereabouts are unknown.

The investigation has prompted questions about what the country’s highest officials knew of the scheme. It has also awakened memories of Zelenskyy’s attempt last summer to curtail Ukraine’s anti-corruption watchdogs. He backtracked after widespread street protests in Ukraine and pressure from the European Union, which has pushed the country to address entrenched corruption.

While Ukrainians expressed anger and disbelief at the unfolding scandal, European Commission President Ursula von der Leyen said the EU would disburse Thursday a 6 billion euros ($7 billion) loan to Ukraine and promised more money for Kyiv.

“We will cover the financial needs of Ukraine for the next two years,” she said in a speech to the European Parliament.

The EU is looking into how it can come up with more money for Ukraine, either by seizing frozen Russian assets, raising funds on capital markets, or having some of the 27 EU nations raise the money themselves.

Russian President Vladimir Putin “thinks he can outlast us” in the battle over Ukraine’s future, nearly four years after Russia’s invasion of its neighbor, von der Leyen said.