Ukrainian troops have struck a strategic bridge essential for Moscow to supply its forces occupying the country's south, as Russia pounded several areas in Ukraine with rocket and artillery strikes.

The Ukrainian military struck the Antonivskyi Bridge across the Dnieper River late on Tuesday, the deputy head of the Moscow-appointed administration for the Kherson region, Kirill Stremousov, said.

He said the bridge was still standing but its deck was pierced with holes, stopping vehicles from crossing.

The 1.4 kilometre bridge sustained serious damage in Ukrainian shelling last week, when it took multiple hits. It was closed for trucks but had remained open for passenger vehicles until the latest strike.

Ukrainian forces used the US-supplied HIMARS multiple rocket launchers to hit the bridge, Mr Stremousov said.

The bridge is the main crossing across the Dnieper River in the Kherson region. The only other option is a dam at the hydro-electric plant in Kakhovka, which also came under Ukrainian fire last week but has remained open for traffic.

Knocking the crossings out would make it hard for the Russian military to keep supplying its forces in the region amid repeated Ukrainian attacks.

Early in the war, Russian troops quickly overran the Kherson region just north of the Crimean Peninsula that Russia annexed in 2014. They have faced Ukrainian counterattacks, but have largely held their ground.

The Ukrainian attacks on the bridge in Kherson come as the bulk of the Russian forces are stuck in the fighting in Ukraine's eastern industrial heartland of Donbas where they have made slow gains in the face of ferocious Ukrainian resistance.

Supplies of US weapons such as HIMARS have helped slow the Russian advances.

Russian forces kept up their artillery barrage in the eastern Donetsk region, targeting towns and villages, according to regional governor Pavlo Kyrylenko.

In Bakhmut, a key city on the frontline of the Russian offensive, the shelling damaged a hotel and caused casualties, Mr Kyrylenko said. A rescue operation was under way.

Ukrainian President Volodymyr Zelenskyy claimed that Russian military losses have climbed to nearly 40,000, adding that tens of thousands more were wounded and maimed. His claim couldn't be independently verified.

The Russian military last reported its losses in March, when it said that 1,351 troops were killed in action and 3,825 were wounded.

Gas flow to Europe cut again

Russia's Gazprom on Wednesday halved the amount of natural gas flowing through a major pipeline from Russia to Europe to 20 per cent of capacity.

It's the latest Nord Stream 1 reduction that Russia has blamed on technical problems but Germany calls a political move to sow uncertainty and push up prices amid the war in Ukraine.

The Russian state-controlled energy giant announced on Monday that it would slash flows on the Nord Stream 1 pipeline that runs to Germany because of equipment repairs.

It's raised new fears that Russia could completely cut off gas that is used to power industry, generate electricity and heat homes to try to gain political leverage over Europe as it tries to bolster its storage levels for winter.

Data on the Nord Stream website and the head of Germany's network regulator, Klaus Mueller, confirmed the reduction.

Natural gas prices have surged on Europe's TTF benchmark to levels not seen since early March and are nearly six times higher than they were a year ago.

Soaring energy prices are fuelling record inflation, squeezing people's spending power and heightening concerns that Europe could plunge into recession if it does not save enough gas to get through the cold months.

AP

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