Ukraine has launched a fresh wave of anti-corruption raids on high-profile figures, including one of the country’s richest men, Ihor Kolomoisky.
The home of former interior minister Arsen Avakov was also searched, as part of the apparent purge.
Ukraine has launched an anti-corruption drive and officials said the leaders of the customs service had been fired.
The head of President Volodymyr Zelensky’s party in parliament said Ukraine would change during the war.
“If anyone isn’t ready for change, then the state itself will come and help them change,” said David Arakhamia on the Telegram messaging app.
Ukraine has come under increasing pressure from its Western partners, notably the EU, to tackle corruption. When Mr Zelensky came to power in 2019 he cited the fight against corruption as one of his main priorities.
Kyiv is due to host a summit with leading EU officials this week, seen by Ukraine as highly important in its push for membership of the 27-member union. Kyiv was granted EU candidate status four months after Russia’s invasion, but it was urged to do more to tackle corruption.
Ten leading Ukrainian figures resigned last week, as part of the purge, including Mr Zelensky’s deputy head of office Kyrylo Tymoshenko.
Several deputy ministers and regional governors were also squeezed out. Mr Zelensky said at the time that any internal problems that hindered the state would be cleaned up to help Ukraine’s “rapprochement with European institutions”.
Mr Kolomoisky is one of Ukraine’s best-known individuals and Ukrainian websites published pictures of detectives searching his home in the south-eastern city of Dnipro as he looked on.
The tycoon took on the role of governor of the wider Dnipropetrovsk region in 2014 and played a key role in funding volunteer battalions in response to Russia’s initial landgrab in eastern Ukraine.
However, the US placed him under sanctions for alleged “significant corruption” during his time as governor. He has denied any wrongdoing.
Mr Kolomoisky is also a wealthy businessman involved in Ukrainian media, oil and banking. His TV channel gave Mr Zelensky his break with the comedy series Servant of the People, before he backed the former actor’s bid for the presidency.
In a statement that made no mention of the tycoon, the economic security bureau said it had exposed large-scale embezzlement schemes and tax evasion worth 40bn hyrivnia ($1bn; £880m) by the former management of Ukraine’s two biggest oil firms, Ukranafta and Ukrtatnafta.
There was no initial comment from Mr Kolomoisky, whose companies had a substantial stake in both companies. They were among several strategic businesses transferred to state ownership last November. Weeks earlier, Mr Kolomoisky’s flat was searched in western Ukraine.
In a separate raid, the former interior minister, Arsen Avakov, told Ukrainian media that his home had been searched as part of an inquiry into Ukraine’s purchase of Airbus helicopters six years ago.
Mr Avakov was quoted as saying that nothing had been found and all the contracts had been approved at the time.
The move followed a deadly helicopter crash outside a kindergarten in a suburb of the capital Kyiv that left 14 people dead, including the interior minister, his entourage and a child on the ground.
Referring to the latest anti-corruption swoop as “spring landings”, Mr Arakhamia listed further investigations, including the dismissal of the entire leadership of the customs service. MP Oleksiy Honcharenko said the acting head and two deputies had been fired.
The main tax office in Kyiv was also raided.
