Yulia Navalnaya on Monday vowed to continue her husband Alexei Navalny's fight after his death in a Russian prison last week, for which she blamed the Kremlin.
She spoke as the Kremlin said it had no details about his death, while his mother Lyudmila was denied access to his body for a third day.
Navalnaya's address came shortly before she met European Union foreign ministers in Brussels, where she had been invited after the death of her husband triggered Western outrage.