International rights group are raising the alarm about secret detentions in Ukraine.
Amnesty International and Human Rights Watch published a report this summer detailing the use of torture and secret detentions by both the Ukrainian government and the Russia-backed separatist rebels it is fighting in the country's east.
The two groups said Monday that 13 people have been released from a Security Service of Ukraine compound since the report came out. The groups said, however, that five people are still being secretly detained in a government compound in the city of Kharkiv.
Monday's statement said the release of 13 people "confirms the need to end and investigate these abuses and deliver justice to the victims.''
The fighting in eastern Ukraine has killed more than 9,500 people since it began in 2014.