Ukraine’s president says the Russians are “gradually being pushed out” of the country’s second-largest city in a counterattack that could signal a shift in the momentum of the war.

Russian forces are reportedly been forced back from villages in the Kharkiv region after days of Ukrainian advances, and are now within several kilometres of the Russian border.

The Ukrainian resurgence in Kharkiv, which has been under heavy attack since the beginning of the war, was helping put the region beyond the range of Russian artillery.

President Volodymyr Zelensky was cautious about over-emphasising the successes, saying he did not want to raise the expectations of Ukrainians too high yet.

“We should not create an atmosphere of excessive moral pressure, where victories are expected weekly and even daily,” he said in an overnight video address.

The 92nd Mechanised Brigade confirmed to Reuters it had recaptured four villages north of Kharkiv, pushing Russian forces closer to the border.

“The enemy is trying to prevent our troops from moving further towards the border in the Kharkiv region,” the Ukrainian general staff said, without providing specifics.

A destroyed house in the village of Vilhivka which Ukraine has reclaimed. Photo: Getty

Ukrainian progress could be seen on the ground in Vilhivka, a severely damaged village recaptured by Ukrainian forces weeks ago, but where few civilians had so far dared return.

With the Russians having now been pushed further east in recent days, more people have been venturing back to comb through the wreckage of their homes.

The thump of artillery and swoosh of rocket launchers could be heard from fighting at the front.

East of Vilhivka, Ukrainian forces seemed to be in control of the village of Rubizhne after what appeared to be the fastest advance since Ukraine pushed Russian forces back from Kyiv and the country’s north in April.

“It is burned out, just like all Russian tanks,” a Ukrainian soldier told Reuters outside the village next to the ruins of one Russian tank.

“The weapons are helping a lot, the anti-tank ones.”

Ukraine stops gas flows

Meanwhile, while Kyiv has been forced to shut gas flows to Europe on a route through Russian-held territory, raising the spectre of an energy crisis on the continent.

The move was one of the first times gas shipments to Europe have been directly affected by the conflict which Ukraine blamed on Russian-backed separatists siphoning supplies.

Should the supply cut-back persist, it would be the most direct impact so far on European energy markets of the war.

Apart from the east, Russia has seized a swathe of southern Ukraine, where Kyiv and its Western allies say they believe Moscow intends to organise a fake referendum on independence or annexation to make its occupation permanent.

The Kremlin said on Wednesday it was up to residents living in the Russian-occupied Kherson region to decide whether they wanted to join Russia, but any such decision must have a clear legal basis.

Earlier, TASS news agency quoted an official in the Russian-controlled administration as saying the region planned to ask President Vladimir Putin to incorporate it into Russia.

Russian forces have also continued to bombard the Azovstal steelworks in the southern port of Mariupol.

Ukraine’s general staff said Moscow was trying to capture the last bastion of Ukrainian resistance in the ruined city.

The Azov Regiment holed up inside it said Russia was bombing the factory from the air and trying to storm it. Reuters was unable to independently verify the reports of fighting there.

-with AAP