Ukraine's anti-corruption agencies have begun searching the apartment of President Volodymyr Zelensky's chief of staff Andriy Yermak, BBC reports.
One of the two agencies, anti-corruption bureau Nabu, confirmed that its investigative searches had been authorised and said further details would follow.
A corruption scandal has engulfed several figures close to Zelensky, though neither he nor his right-hand man Yermak have been accused of any wrongdoing.
Andriy Yermak is the president's closest aide and has had his ear throughout Russia's full-scale invasion. He is also Kyiv's lead negotiator in peace talks with the US, but his position has come increasingly under threat from critics calling for him to go.
Yermak, 54, confirmed on social media that both Nabu and the specialised anti-corruption prosecutor's office (Sap) were "conducting procedural actions at my home" and had full access to his apartment, with his lawyers on site.
"From my side, there is full co-operation," said the chief of staff, who has not been named as a suspect.
The searches come at a very awkward moment for Zelensky and his closest ally, 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.
One of the main sticking points for Ukraine is Russia's demand for Ukraine to hand over the territory it still controls in the eastern Donetsk region. "If they don't withdraw, we'll achieve this by force of arms," Vladimir Putin said on Thursday.
Yermak, who wields enormous influence at the top of government in Kyiv, underlined his leading role in the 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".
However, Putin has been emboldened by minor territorial gains by Russian forces, claiming their offensive "is practically impossible to hold back".
Meanwhile, Zelensky's own position has been weakened by the domestic corruption scandal, and Russia's president has long questioned his legitimacy as leader.
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.
