Ukrainian President Volodymyr Zelenskiy says personnel changes are being carried out at senior and lower levels as the highest-profile graft allegations since Russia's invasion threaten to dampen Western enthusiasm for the Kyiv government.
Reports of a new scandal in Ukraine, which has a long history of shaky governance, come as European countries bicker over giving it German-made Leopard 2 tanks - the workhorse of armies across Europe that Kyiv says it needs to break through Russian lines and recapture territory.
"There are already personnel decisions - some today, some tomorrow - regarding officials at various levels in ministries and other central government structures, as well as in the regions and in law enforcement," Zelenskiy said in his nightly video address late on Monday.
Zelenskiy did not identify the officials to be replaced.
Several Ukrainian media outlets have reported that cabinet ministers and senior officials could be sacked imminently.
The deputy head of Ukraine's presidential office, Kyrylo Tymoshenko, later said he had asked Zelenskiy to relieve him of his duties.
He did not give a reason but media reported earlier he might be part of a shake-up.
On Sunday, anti-corruption police said they had detained the deputy infrastructure minister on suspicion of receiving a $US400,000 ($A569,071) kickback over the import of generators last September, an allegation the minister denies.
A newspaper accused the defence ministry of overpaying suppliers for soldiers' food.
The supplier has said it made a technical mistake and no money had changed hands.
David Arakhamia, head of Zelenskiy's Servant of the People party, said officials should "focus on the war, help victims, cut bureaucracy and stop dubious business".
"We're definitely going to be jailing actively this spring. If the humane approach doesn't work, we'll do it in line with martial law," he said.
Front lines in the war have been largely frozen in place for two months despite heavy losses on both sides.
Ukraine says Western tanks would give its troops the firepower to break Russian defensive lines.
But Western allies have been unable to reach an agreement on arming Kyiv with tanks, wary of action that could trigger Russian escalation.
Germany, which must approve Leopard re-exports, has said it is willing to act quickly if there is a consensus among allies.
Polish Prime Minister Mateusz Morawiecki said Warsaw would seek permission to send Leopard tanks to Kyiv and was trying to get others on board.
Germany was not blocking the re-export of Leopard tanks to Ukraine, the European Union's top diplomat said on Monday.
American lawmakers have pressed their government to export M1 Abrams battle tanks to Ukraine, saying even a symbolic number would help push European allies to do the same.
Britain has said it will supply 14 Challenger 2 tanks.
French President Emmanuel Macron said he did not rule out the possibility of sending Leclerc tanks.
Russia has sought to apply its own pressure.
"All countries which take part, directly or indirectly, in pumping weapons into Ukraine and in raising its technological level bear responsibility" for continuing the conflict, Kremlin spokesman Dmitry Peskov said.
Meanwhile, Russian forces pounded Donetsk in Ukraine's east.
Ukrainian forces repelled 11 attacks, 10 of them in the Donetsk region, including in the areas of the town of Bakhmut and the village of Klishchiivka to the south, Ukraine's military said on Tuesday.
Last week, Russia claimed the capture of Klishchiivka.
Russian forces have been pressing for months for control of Bakhmut but with limited success.
Reuters could not verify battlefield reports.
On Monday, the new general in charge of Russia's military operations in Ukraine warned that modern Russia had never seen such "intensity of military hostilities", forcing it to carry out offensive operations.
"Our country and its armed forces are today acting against the entire collective West," Chief of the General Staff Valery Gerasimov told the news website Argumenty i Fakty.