Russia has established a secret military biological laboratory complex on an island in Tver Oblast where it is experimenting with dangerous viruses and other pathogens.

Axar.az reports, citing Ukrainian media, that Ukraine’s Defence Intelligence said that the facility, officially known as the “Center for Experimental Physiology,” is located on Lisiy Island in the middle of the Vyshny Volochyok Reservoir.

It conducts biological experiments under the guise of veterinary and physiological research for the Russian armed forces.

The waters around the island have been closed to fishing, swimming and boating since 2023 and designated a specially protected area.

The agency warned that the reservoir supplies drinking water to several settlements and feeds the Tvertsa River, which flows into the Volga. It said any release of dangerous pathogens or chemicals could potentially cause widespread outbreaks.

The intelligence service said the complex was established on orders from Russian President Vladimir Putin as a facility intended to “ensure Russia’s defense capability and security” and was formally incorporated into the Federal Medical-Biological Agency.

Ukraine’s intelligence service also claimed that the facility is heavily guarded and protected by air-defense systems.