The strikes, reported by the region's local governor and the Russian military, followed Moscow's capture of the Ukrainian city of Lysychansk on Sunday, a move that handed it total control of the Luhansk region, one of its main war aims.

Taking full control of Donetsk, the other region in Donbas, the industrialised eastern part of Ukraine that has become the stage of the biggest battle in Europe in generations, is another goal of what Moscow calls its "special military operation."

Ukrainian forces which retreated from Lysychansk at the weekend took up new defensive lines in Donetsk on Tuesday, according to Serhiy Gaidai, the Ukrainian governor of Luhansk.

In a foretaste of what is likely to follow, Pavlo Kyrylenko, the governor of neighbouring Donetsk, said on TV that his region had been hit overnight.

"Sloviansk and Kramatorsk came under shelling. They are now also the main line of assault for the enemy from the Lyman direction ... there is no safe place without shelling in the Donetsk region," he said.

The Russian defence ministry, which says it does not target residential areas, said it had used what it called high-precision weapons to destroy command centres and artillery in Donetsk, where Ukraine still controls major cities.

President Vladimir Putin has told troops involved in capturing Luhansk who would also be part of any attempt to capture cities in Donetsk, to "rest and recover their military preparedness", while units in other parts of Ukraine keep fighting.

Both sides have suffered heavy casualties in the fight for Luhansk, particularly during the siege of the twin cities of Lysychansk and Sievierodonetsk. Both have been left wrecked.

A Reuters reporter who visited Lysychansk on Monday found widespread destruction and few residents in a city that was once home to nearly 100,000 people.

Those who were left surveyed bullet-riddled up-ended Ukrainian police cars, hulking local government buildings scorched by shell fire and the damaged golden dome of an Orthodox church.

Since the outset of the conflict, Russia has demanded that Ukraine hand both Luhansk and Donetsk to Moscow-backed separatists, who have declared their independence.

'"This is the last victory for Russia on Ukrainian territory," Oleksiy Arestovych, adviser to President Volodymyr Zelenskiy, said in a video posted online.

"These were medium-sized cities. And this took from 4th April until 4th July - that's 90 days. So many losses."

Arestovych said besides the battle for Donetsk, Ukraine was hoping to launch counter offensives in the south of the country.

"Taking the cities in the east meant that 60 per cent of Russian forces are now concentrated in the east and it is difficult for them to be redirected to the south," he said.

"And there are no more forces that can be brought in from Russia. They paid a big price for Sievierodonetsk and Lysychansk."

Some military experts reckoned the hard fought victory had brought Russian forces little strategic gain, and the outcome of what has been dubbed the "battle of the Donbas" remained in the balance.

"I think it's a tactical victory for Russia but at an enormous cost," said Neil Melvin of the RUSI think tank in London.

"The Russians may declare some kind of victory, but the key war battle is still yet to come," he said.

Melvin said the decisive battle for Ukraine was likely to be fought not in the east, where Russia is mounting its main assault, but in the south, where Ukraine has begun a counter-offensive to recapture territory around the city of Kherson.

Australian Associated Press