Kyiv on Tuesday announced the dismissal of a dozen top officials in its biggest political shakeup following the country's first major corruption scandal linked to the Russian invasion.
Ukraine has long suffered endemic corruption, but Moscow's nearly year-long full-scale war has overshadowed government efforts to stamp out graft.
Western allies, which have allocated billions of dollars in financial and military aid to Kyiv to counter Russian troops, have often preconditioned such support on anti-corruption reforms.
Ukrainian President Volodymyr Zelensky said in his evening address on Tuesday that the clean-up was necessary and that additional measures would be taken.
"It is fair, it is needed for our defence, and it helps our rapprochement with European institutions," he said. "We need a strong state, and Ukraine will be just that."
Presidential aide Mykhaylo Podolyak said Zelensky had focused on "key priorities of the state" in dismissing the officials, who include governors of regions that have seen heavy fighting and deputy cabinet ministers.
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"During the war, everyone should understand their responsibility," Podolyak tweeted.
The shakeup came after a Ukrainian deputy minister of development of communities and territories, Vasyl Lozynskiy, was sacked at the weekend following his arrest on suspicion of embezzlement.
Photographs released by the National Anti-Corruption Bureau showed stashes of cash seized at Lozynskiy's office.
The 36-year-old was accused of receiving a $400,000 bribe to "facilitate" the purchase of generators at inflated prices as Ukraine struggles with electricity shortages following Russian strikes on the energy grid.
On Tuesday, key presidential aide Kyrylo Tymoshenko, who has worked with Zelensky since his 2019 election, announced his resignation.
The 33-year-old posted a picture of himself holding a handwritten resignation letter, thanking the president for the "opportunity to do good deeds every day and every minute".
Tymoshenko was implicated in several scandals, including over the alleged personal use last October of an SUV donated to Ukraine for humanitarian purposes.
Oleg Nemchinov, a senior government official, also announced the departure of five regional governors and four deputy ministers.
They include the heads of the central Dnipropetrovsk region, the northeastern Sumy region, the southern regions of Zaporizhzhia and Kherson, as well as the region surrounding the capital Kyiv.
Nemchinov additionally announced the dismissal of two deputy ministers of development of communities and territories, and a deputy minister of social policy.
The defence ministry separately announced the resignation of deputy minister Vyacheslav Shapovalov, who oversaw the army's logistical support.
It came after the ministry was accused of signing food contracts at prices two to three times higher than current rates for basic foodstuffs.
The ministry insisted the accusations were "unfounded and baseless" but said Shapovalov's departure would "preserve the trust of society and international partners".
Deputy Prosecutor General Oleksiy Symonenko also resigned, following media reports that he had holidayed in Spain, reportedly using a car belonging to a Ukrainian business.
The United States welcomed the dismissals and said that none of the billions of dollars in US war assistance was known to have been involved.
"The Ukrainian people have been very clear about their desire for good governance and transparency," said State Department spokesman Ned Price.
Despite being vocal about fighting corruption, Zelensky himself has been embroiled in corruption scandals in the past.
In 2021, the so-called Pandora Papers obtained by the International Consortium of Investigative Journalists said Zelensky used a network of offshore companies to buy three upmarket properties in London.
His office said at the time that Zelensky, who is a former actor and comedian, created the offshore companies to protect himself against the "aggressive actions" of the "corrupt" regime of pro-Russian President Viktor Yanukovych.
Transparency International ranked Ukraine 122 out of 180 in its corruption ranking for 2021.