Russia is planning a second major military base near the border with Ukraine, where NATO accuses Russian troops of helping pro-Moscow separatists fight Kiev’s forces.
The new base will house 5,000 soldiers and heavy weaponry, according to public documents and people working at the site.
It is further east than one under construction in Belgorod region reported by Reuters earlier this month but still close to the border with separatist-held parts of Ukraine’s eastern Luhansk region, where there has been heavy fighting.
The bases are part of a Russian military buildup along a new line of confrontation with the West, running from the Black Sea in the south to the Baltic in the north, which carries echoes of the Cold War-era “Iron Curtain”.
Russia has also increased its military presence in Syria.
NATO and the pro-Western government in Ukraine say Moscow uses bases on the border with the former Soviet republic as staging posts to send troops across into areas where almost 8,000 people have been killed since April last year.