Russia is undertaking a major factory expansion in remote Siberia to ramp up production of a powerful explosive used in artillery shells and other munitions in the war in Ukraine, a Reuters review of publicly available state documents has found.

Moscow's ability to muster more shells than Ukraine has played an important part in Russia's battlefield successes during the conflict.

The additional explosive anticipated from the project, which has not previously been reported, could help increase Moscow's firepower significantly at a time when Ukraine and its Western allies have been stepping up production of ordnance needed to thwart Russian advances, three defence analysts said.