Jails in the Russian capital are overcrowded after weeks of protests in support of Kremlin critic Alexei Navalny.
Demonstrations have been taking place in cities across the country since Navalny was arrested on his return to Russia last month.
Thousands of people have been arrested across the country, as police cracked down on what they say were illegal demonstrations.
In Moscow, more than 800 people are still being held in vastly overcrowded cells and facilities. A video taken by one detainee shows 28 men crammed inside a holding cell intended for eight inmates, with no mattresses on the cots and a filthy pit latrine-like toilet.
More than 11,000 protesters were reportedly detained across the country during two weekends of pro-Navalny rallies last month and in Moscow and St. Petersburg last week after he was ordered to serve nearly three years in prison.
In Moscow, jails quickly filled up as hundreds of people were sentenced by the courts. Most of the detained were sent to the Sakhorovo immigration detention centre on the outskirts of the city.
Kremlin spokesman Dmitry Peskov has acknowledged the overcrowding of the detention centres and blamed the problem on the protesters themselves.
“This situation wasn’t provoked by law enforcement; it was provoked by participants of unauthorized rallies,” Peskov said.
Listen to Galina Polonskaya's report from Moscow by clicking on the media player above.