Marianna Budanova is the wife of Kyrylo Budanov, who heads Ukrainian military intelligence agency GUR, which has been prominently involved in clandestine operations against Russian forces throughout the 21-month war.
Budanov's public profile has surged in Ukraine, where he is portrayed as a behind-the-scenes mastermind of efforts to strike back at Russia. In Russian media he is a hate figure.
If confirmed as deliberate, the alleged poisoning of his wife would represent the most serious targeting of a high-profile Ukrainian leadership figure's family member since Moscow began its invasion in February last year.
Ukraine's military intelligence and domestic security services did not respond to requests for comment.
The reports did not make any suggestions of who was behind the alleged poisoning or clarify when it took place.
One media outlet, Babel, cited an unnamed source who said Budanova had been in hospital, and was finishing a course of treatment for the effects of the poisoning. Public broadcaster Suspilne and online outlets Ukrainska Pravda and RBC Ukraina also reported she had been poisoned.
Ukrainska Pravda cited a source saying the poison had likely been administered in her food and that several other GUR staff members had also been poisoned.
Russian media has reported that a court in Moscow had arrested Budanov in absentia in April on terrorism charges.
Moscow has previously blamed Ukrainian secret services for the murders of a pro-war Russian blogger and a pro-war journalist on Russian soil. Kyiv denies involvement in those deaths.
Budanov has previously said he would "keep killing Russians anywhere on the face of this world until the complete victory of Ukraine".
(Reporting by Max Hunder and Tom Balmforth; editing by Barbara Lewis)
