Editor's note: This is a developing story.
Ukraine's military intelligence carried out a large-scale cyberattack in Russia's Tatarstan on May 3, a source in the agency confirmed to the Kyiv Independent.
The attack reportedly targeted internet providers and mobile operators in the Russian republic.
The Ukrainian media outlet NV, citing sources, reported that the Alabuga special economic zone was the main target.
NV wrote that it was a denial of service (DDoS) attack, which effectively blocked internet access in Tatarstan's capital of Kazan, Russia's fifth largest city.
The press service for Tattelecom, one of the largest telecommunications operators in the republic, said that it was the most powerful cyberattack on its networks in the history of the company.
Alabuga, which reportedly hosts a factory that produces Shahed-type drones, has previously been the target of Ukrainian attacks.
Ukrainian forces struck drone factories in the cities of Yelabuga and Nizhnekamsk in April, located about 1,300 kilometers (around 800 miles) away from the Russia-Ukraine border, Ukraine's military intelligence agency reported.
The strikes, which were some of Ukraine's longest-distance attacks into Russian territory, were reportedly carried out with domestically-produced weapons.