Ukrainian troops have been forced to withdraw from some parts of Bakhmut in the face of a renewed Russian assault on the ruined battlefield city, Britain said on Friday, with Moscow pressing to achieve a victory before Ukraine’s expected counteroffensive.

Ukrainian officials say Russia has been drawing down troops from other areas on the front for a major push on Bakhmut, which Moscow has been trying to capture for nine months to reenergize the all-out invasion it launched more than a year ago.

Western countries have in the past pointed to acrimony between the Russian defence ministry (MoD) and the country’s main mercenary force Wagner as a major Russian weakness.

“Russia has re-energised its assault on the Donetsk Oblast town of Bakhmut as forces of the Russian MoD and Wagner Group have improved cooperation,” Britain’s military said in a daily briefing note. “Ukrainian forces face significant resupply issues but have made orderly withdrawals from the positions they have been forced to concede,” it said.

Near Bakhmut, soldiers from a Ukrainian artillery unit were loading shells into a Soviet-era howitzer and firing towards the front line, where they said Russia had massed its foot soldiers.

“Our target in that direction is mostly infantry. There is a big concentration of the Russian Federation’s ‘human factor’,” said Dmytro, the artillery unit’s 44-year-old commander.

The gun thundered as the unit blasted three shells, the first to find the range, the second to adjust aim.

“The third one is finishing off. Most likely, I hope, the infantry they spotted was eliminated.”

Bakhmut, which held around 70,000 people before the war, has been Russia’s main target in a massive winter offensive that has so far yielded scant gains despite infantry ground combat of an intensity unseen in Europe since World War II.

Ukrainian deputy defence minister Hanna Maliar said Russian commanders had redirected troops to Bakhmut from other areas.

“The enemy is using its most professional units there and resorting to a significant amount of artillery and aviation,” she wrote on the Telegram messaging app.

“Every day, the enemy carries out in Bakhmut from 40 to 50 storming operations and 500 shelling episodes.”