Russia was expelled from the Council of Europe, an international human-rights monitor, in March 2022, though it had technically remained a party to its European Convention for the Prevention of Torture.

The landmark agreement aims to strengthen the rights of persons deprived of their liberty and empowers monitors to visit prisons and detention centres.

On Monday, Putin signed a law denouncing the convention.

Explanatory notes to the law, which was passed earlier by Russia’s rubber-stamp parliament, accused the Council of Europe of “discrimination” by refusing to appoint a Russian representative to statutory bodies.

Russia’s foreign ministry said last month that pulling out of the convention would not “harm” Russian citizens and that Russia “remains committed to its international human rights obligations”.

But two UN special rapporteurs said earlier this month the move to pull out of the treaty “raises red flags about what is going on behind bars” in Russian jails.

The decision to quit the body comes after international watchdogs have repeatedly denounced alleged human rights violations by Russian authorities during Moscow’s offensive in Ukraine.

Last week, the Organization for Security and Co-operation in Europe said Moscow was responsible for “widespread and systematic violations” of international law in the treatment of Ukrainian prisoners of war, including “arbitrary killings”.

A UN rights office report has also concluded that Russia “has subjected Ukrainian civilian detainees to consistent patterns of serious violations” of international law.