The searches come at a very awkward moment for Zelensky and his chief of staff, with US Army Secretary Dan Driscoll due to arrive in Kyiv by the end of this week as US President Donald Trump pushes ahead with a draft peace plan. US officials are heading to Moscow next week.
Yermak underlined his leading role in those negotiations when he told The Atlantic website hours before news of the searches emerged that “as long as Zelensky is president, no-one should count on us giving up territory. He will not sign away territory”.
The corruption scandal has rocked Ukraine this month, with investigators linking several leading public figures to an alleged $100m (£75m) embezzlement scandal in the energy sector.
The two anti-corruption agencies, Nabu and Sapo, said they had uncovered an extensive scheme to take kickbacks and influence state-owned companies including state nuclear energy firm Enerhoatom.
A number of suspects have already been charged in the scandal that has outraged public opinion because of allegations that money was diverted from key infrastructure projects vital for safeguarding Ukrainian power supplies.
Russian attacks have badly damaged Ukraine’s energy infrastructure and Ukrainians across the country have had to cope with only a few hours of electricity a day.
Zelensky has already fired two ministers and several suspects have been detained in the scandal. One of the president’s former business associates, Timur Mindich, has fled the country.
He was co-owner of the TV studio where Zelensky’s acting career took off before he was elected president.