Russia’s Memorial human rights group currently estimates there are 297 political prisoners in Russia, up from 50 four years ago . It lists 77 of the most high-profile cases on its website, including Crimean filmmaker Oleg Sentsov, who is serving a long jail sentence on terrorism charges, and two teenage girls charged with extremism.

The number of political prisoners in Russia has grown sixfold since 2015, a prominent member of the pro-democracy movement Open Russia has said.

“In the last four years, the number of political prisoners in Russia has grown sixfold,” Open Russia coordinator Vladimir Kara-Murza said at a session of the UN Human Rights Council.

Kara-Murza called on the UN body to “speak out on their behalf and to seek justice for those who are deprived of it at home.”

Memorial slammed Russia’s criminal law last week for “severely” restricting Russia’s fundamental freedoms.

Founded by exiled opposition politician Mikhail Khodorkovsky, Open Russia was blacklisted by Russian prosecutors as an “undesirable organization” in 2017. The group supports projects which it believes will promote and strengthen democracy in the country.