As reported by Censor.NET, this was announced by Chief of the NABU Nazar Kholodnytskyiv to 112 Ukraine TV channel.
NABU's spokesperson is to provide official commentary soon.
Media report that investigators who arrived at the scene have presented a court ruling on the search. The ruling is based on investigation into illegal eavesdropping of phone conversations by NABU officers. It is not reported whose conversations those were.
NABU denied the investigators to the premises, and Alpha special unit officers were called to the scene.
Earlier, Rada's anti-corruption committee approved a bill allowing NABU to conduct independent eavesdropping of communication channels.
Related materials: National Anti-Corruption Bureau