Human Rights Watch and Amnesty International have called on Russian authorities to take measures to end a campaign of "persecution" against human rights defenders in Chechnya and to offer them protection.
The rights groups' December 15 joint statement comes two days after the office of the Grozny branch of the Committee to Prevent Torture (KPP) was set on fire.
Two KPP employees in Chechnya's capital have been followed by armed men, detained for hours by police, and had personal computers and phones confiscated.
Kremlin-backed Chechen leader Ramzan Kadyrov has implied KPP head Igor Kalyapin helped finance an armed attack in Grozny on December 4 that left 14 police dead.
Kalyapin had criticized Kadyrov for saying that relatives of militants involved in deadly attacks would be expelled from Chechnya and their homes razed.
Eight homes were subsequently destroyed by fire.
Anna Neistat, Amnesty International's senior director of research, said Kadyrov "appears to be waging a personal campaign against" the KPP and Kalyapin.