The mother of a young Italian researcher who was tortured and slain in Egypt in 2016 has begun a fast to protest the arrest of an Egyptian activist.

Paola Regeni, whose son, Giulio, had been conducting PhD research in Cairo on labor movements, says she will alternate days of fasting with their family lawyer, starting Monday, to demand the release of activist Amal Fathy.

Fathy's husband runs a rights group which has been helping the Regeni family. Amnesty International says the woman was arrested last week after she posted a video online lashing out at the state for deteriorating public services, unchallenged sexual harassment and other reasons.

Italian prosecutors say Regeni had been under Egyptian police surveillance until his disappearance. Egypt's security services have denied any role in Regeni's murder.