GENEVA: The human rights situation in Russia has significantly deteriorated since it invaded Ukraine in February last year, a United Nations expert said on Monday, describing a "systematic crackdown" on civil society and calling for redress.

The report by Special Rapporteur Mariana Katzarova alleges that Russian authorities have carried out mass arbitrary arrests of critics of the war and says those detained risk death due to the "persistent use of torture and ill-treatment".

It is the first time the 16-year-old U.N. Human Rights Council (HRC) has been mandated to examine the record of one of its so-called "P5" members, which hold permanent seats on the Security Council.

Kremlin spokesperson Dmitry Peskov said he could not comment for the time being because he had yet seen the report.

Moscow has previously called criticism of its domestic rights record unfounded and denied targeting civilians in Ukraine, where it says it is carrying out a "special military operation" to destroy military infrastructure.

"(The expert) has documented the recent legislative restrictions that are being used to muzzle civil society and punish human rights activists and others for their anti-war stance," the report said in its conclusions.

"The often-violent enforcement of these laws and regulations has resulted in a systematic crackdown on civil society organizations that has closed civic space and independent media," it said.

Since Russia's invasion of Ukraine, Moscow has passed stronger laws to punish dissenters and perceived traitors.

The U.N. expert Katzarova, a former journalist from Bulgaria who led investigations during the two Chechen wars for Amnesty International, also referred to attempts by Russia to obstruct her mandate, saying such actions showed "a lack of political will to uphold its human rights obligations".

Moscow has previously said it would not cooperate with the probe.

A debate on the report's findings is expected at the HRC's ongoing session in Geneva on Thursday. European Union countries are set to seek a renewal of Katzarova's mandate. More than a dozen non-governmental organisations have written to diplomats in Geneva asking them to support the renewal, a letter showed. (Reporting by Emma Farge and Gabrielle Tétrault-Farber; Editing by Rachel More and Gareth Jones)