Russia has significantly bulked up its forces around the devastated city of Bakhmut in the east and has switched its troops from a defensive posture to taking “active actions”, a Ukrainian military commander said on Monday.

Russia captured Bakhmut, the scene of some of the most intense fighting of the 20-month war, in May. Ukraine has been on the counteroffensive since June to try to retake occupied land in the south and east, including the town.

“In the Bakhmut area, the enemy has significantly strengthened its grouping and switched from defence to active actions,” General Oleksandr Syrskyi, commander of the ground forces, wrote on Telegram messenger.