Russia's Federal Security Service has detained four people in the Republic of Adygea and Omsk Region on suspicion of cooperating with Ukrainian intelligence services.

The detainees include three Russian citizens and one foreign national, according to TASS.

The suspects collected information about Russian military personnel involved in what Moscow calls its "special military operation," as well as facilities belonging to the defence industry and fuel and energy sectors.

The information was gathered to prepare sabotage operations and terrorist attacks. The suspects are also accused of distributing online materials calling for terrorist activities.

The suspects communicated with their Ukrainian handlers through Telegram. In exchange for their cooperation, they were reportedly promised substantial financial rewards and assistance in relocating to the European Union.

The items potentially linked to criminal activities were discovered during searches involving one of the detainees.

Criminal cases have been opened under several articles of the Russian Criminal Code, including high treason, preparation for a terrorist attack and sabotage.

All four suspects have been remanded in custody. The charges carry penalties of up to life imprisonment.