It came as Russia and Ukraine swapped 150 prisoners of war each and UK foreign secretary David Lammy met with Ukrainian president Volodymyr Zelensky in Kyiv.

A series of drone attacks by Ukraine on Russia's energy facilities have sparked fires in recent days at a major oil refinery in the Volgograd region, as well as at the Astrakhan gas processing plant.

There are increasing reports from the front about massive Ukrainian drone attacks on targets in Russia. In response, Moscow has deployed a record number of drones in recent months. "We have a positional war on both sides,