More than 95% of the Ukrainian prisoners of war and 85% of the civilian detainees reported being tortured or ill-treated, often repeatedly, a UN official said.
Once a leading liberal voice in parliament and often critical of the government, Yabloko later lost its bloc of seats in the State Duma as the Kremlin tightened its grip on Russian politics.
Large-scale Russian missile strikes on Ukrainian cities have become almost routine in recent weeks, with Moscow exploiting Ukraine's critical shortage of interceptors for the US-made Patriot systems.
Ukrainian forces also hit two Russian military patrol boats in the Black Sea and vessels belonging to Moscow's shadow fleet, which it uses to evade Western restrictions on its oil exports.
US-led talks on ending Europe's deadliest conflict since World War II have been effectively frozen since February, when the United States and Israel launched joint strikes on Iran.
