Ukrainian President Volodymyr Zelenskyy has vowed to keep defending the besieged city of Bakhmut, where Russia is hoping to make its first major wartime gain.

Amidst some of the bloodiest fighting of the more than one-year long war, Moscow said capturing the city would be a step towards its major objective of seizing the full territory of the surrounding Donbas region.

The intense battle has depleted both sides' artillery reserves, with thousands of shells fired daily along the eastern and southern fronts.

Ukraine's European allies are working on a deal to procure more ammunition for the fight.