BERLIN (AP) — Russian forces carried out widespread and systematic torture of civilians who were detained in connection with its attack on Ukraine, summarily executing dozens of them, the United Nations human rights office said Tuesday.

The global body interviewed hundreds of victims and witnesses for a report detailing more than 900 cases of civilians, including children and elderly people, being arbitrarily detained in the conflict, most of them by Russia.

The vast majority of those interviewed said they were tortured and in some cases subjected to sexual violence during detention by Russian forces, the head of the UN human rights office in Ukraine said.

“Torture was used to force victims to confess to helping Ukrainian armed forces, compel them to cooperate with the occupying authorities or intimidate those with pro-Ukrainian views,” said Matilda Bogner.

The report, which covers a 15-month period from the start of the Russian invasion to May 2023, also documented 75 cases of arbitrary detention by Ukrainian security forces, saying a significant proportion of these also amounted to enforced disappearances.

More than half of those detained by Ukrainian forces also reported being tortured or mistreated, usually while they were being interrogated or immediately after arrest, said Bogner.

Ukraine gave UN investigators “unimpeded confidential access” to detainees at official detention centers, with the exception of a group of 87 Russian sailors, she said.

“The Russian Federation did not grant us such access, despite our requests,” Bogner said.

The UN rights office has previously documented the detention and summary execution of Ukrainian prisoners of war by Russia. The latest report found that Russian forces also carried out at least 77 summary executions of civilians.

Those detained included local officials, humanitarian volunteers, priests and teachers, many of whom were held incommunicado in “deplorable conditions,” the report found.

UN experts found no evidence that Russian authorities have investigated allegations of abuse by their own forces and the report expressed concern over a bill that would exempt perpetrators from criminal liability for crimes committed in occupied parts of Ukraine under some circumstances.

“This would violate the state’s obligation to investigate and prosecute serious violations of international humanitarian law and gross violations of international human rights law,” Bogner said.

While Ukraine has launched criminal probes against Russian forces over the detention of civilians, resulting in 23 convictions, the UN rights office said it wasn’t aware of any investigations against Ukraine’s own forces for such violations.

Bogner said Ukrainian laws on detention for national security reasons “appear to go beyond what is permissible under international law, even during a public emergency, and have facilitated arbitrary detention.”

She urged both sides to provide information to relatives on the whereabouts and fate of people detained and to release any civilians who remain arbitrarily detained.