Ukrainian forces are coming under increasing pressure in the heavily contested city of Bakhmut in eastern Ukraine, the site of some of the bloodiest battles to date, as the Russian invasion is 12 days away from its first anniversary.

The head of the Russian mercenary group Wagner claimed on Sunday that his private army has captured a suburb of Bakhmut amid heavy fighting. Ukrainian officials have not confirmed this.

Yevgeny Prigozhin said his mercenary units would go on to take Bakhmut itself, about seven kilometres away.

The months-long battle over Bakhmut has been particularly fierce and costly for both Russian forces and Ukrainian defenders.

The British Ministry of Defence tweeted, citing daily figures released by the Ukrainian General Staff, that Russia “has likely suffered its highest rate of casualties since the first week of the invasion of Ukraine”.

Although London could not verify the figures it believes the information is “likely accurate.”

It said average Russian casualties for the last seven days were 824 per day, more than four times the rate reported in June-July. But “Ukraine also continues to suffer a high attrition rate”, it added.

Reasons for the increased casualty rate likely included a “lack of trained personnel, coordination, and resources across the front,” the ministry wrote, pointing to Russia’s failure to seize the strategic town of Bakhmut as an example.

Apart from hefty casualties on the front, Ukrainian citizens are suffering from periodic blackouts as Russia targets key infrastructure.

On Sunday, Ukrainian electricity production was restored after the latest Russian rocket attacks targeting power infrastructure, according to Ukrainian Energy Minister German Galushchenko.

Ukrainian power production matched consumption on Sunday, Minister Galushchenko said. Repair work had brought nuclear power plants back on the electrical grid, although he pointed out that power outages remained in some areas due to damage to distribution networks.

“There are problems delivering electricity to all customers,” he said.

All nine reactor blocks of the Ukrainian-controlled nuclear power plants have been reconnected to the grid, the minister said. The country’s largest nuclear plant is located in the Russian-occupied Zaporizhzhya region and is not among the plants supplying the grid.

Moscow has repeatedly targeted energy infrastructure in waves of missile attacks.

Meanwhile as Russia battles to overpower the east, seizing Bakhmut would bring Moscow closer to the overpowering the whole Donetsk region, one of the Kremlin’s stated aims in the war.

Ukrainians suspect Russian leader Vladimir Putin wants to create some sort of progress with new offensives before the war’s first anniversary on February 24.

In most cases, the information from the war zone can hardly be verified by independent sources.

Abroad, Ukrainian President Volodymyr Zelensky continued to call for more support to help Kiev prevail, including measures targeting Moscow’s nuclear energy sector.

“It is not easy. There is some resistance,” President Zelensky said during his nightly video message.

He noted that sanctioning Russia’s oil was also difficult but now those sanctions were in effect, indicating that the nuclear energy sector could also be targeted.

Earlier in the day, the Ukrainian leader announced that 199 Russians had been put on a national sanctions list, including representatives of Russian nuclear power plant operator Rosenergoatom.

A Ukrainian was also punished for allegedly siding with Moscow at the Zaporizhzhya nuclear power plant captured by Russia, he said.