The Ukrainian prosecutor general has charged a Russian soldier for the killing of a 62-year-old civillian in the first war crime trial in the ongoing war with Russia, as the Ukrainian government investigates over 10,700 allegations of war crime committed by Russian solders since the beginning of the invasion.

Prosecutor General Iryna Venediktova said her office charged Sgt Vadin Shyshimarin, 21, in the killing of an unarmed 62-year-old civilian who was gunned down while riding a bicycle on February 28.

Shyshimarin, who served with a Russian tank unit, is accused of firing through a car window on the man in the northeastern village of Chupakhivka. If convicted, he could be sentenced to up to 15 years in prison. However, it was not said when the trial would start.

Of the 10,700 alleged war crimes they are investigating, Venediktova's office said they have identified over 600 suspects.?

Many of these alleged atrocities came to light last month after Russian forces withdrew from the area around the Ukrainian capital Kyiv and from the country's north to focus on the country's eastern Donbas region. This withdrawal exposed mass graves and streets and yards strewn with bodies in towns such as Bucha. Residents told of killings, burnings, rape, torture, and dismemberment.

Volodymyr Yavorskyy of the Centre for Civil Liberties said the Ukrainian human rights group will be closely following Shyshimarin's trial to see if it is fair.?

"It's very difficult to observe all the rules, norms and neutrality of the court proceedings in wartime," he said.

On the economic front, Ukraine shut down one of the pipelines that carry Russian gas across the country to homes and industries in Western Europe, marking the first time since the start of the war that Kyiv disrupted the flow westward of one of Moscow's most lucrative exports. But the immediate effect is likely to be limited, in part because Russia can divert the gas to another pipeline and because Europe relies on a variety of suppliers.?

Meanwhile, a Kremlin-installed politician in the southern Kherson region, site of the first major Ukrainian city to fall in the war, said officials there want Russian President Vladimir Putin to make Kherson a "proper region" of Russia, meaning Russia shoukd annex it.

"The city of Kherson is Russia," Kirill Stremousov, deputy head of the Kherson regional administration appointed by Moscow, told Russia's RIA Novosti news agency.

That raised the possibility that the Kremlin would seek to break off another piece of Ukraine as it tries to salvage an invasion gone awry. Russia annexed Ukraine's Crimean Peninsula, which borders the Kherson region, after a disputed referendum in 2014. It was denounced as illegal and was rejected by most of the international community.

Kherson, a Black Sea port of roughly 3,00,000, provides Crimea with access to fresh water and is seen as the gateway to wider Russian control over southern Ukraine.

Kremlin spokesman Dmitry Peskov said it would be "up to the residents of the Kherson region after all to decide whether such an appeal should be made or not". He said any move to annex territory would have to be closely evaluated by legal experts to make sure it is "absolutely legitimate, as it was with Crimea".

Ukrainian presidential adviser Mykhailo Podolyak mocked the notion of Kherson's annexation, tweeting" "The invaders may ask to join even Mars or Jupiter. The Ukrainian army will liberate Kherson, no matter what games with words they play."

Inside Kherson, people have taken to the streets to decry the Russian occupation. But a teacher who gave only her first name, Olga, for fear of Russian retaliation, said such protests are impossible now because Moscow's troops "kidnapped activists and citizens simply for wearing Ukrainian colours or ribbons". She said "people are scared of talking openly outside their homes" and "everyone walks on the street quickly".

She added, "All people in Kherson are waiting for our troops to come as soon as possible. Nobody wants to live in Russia or join Russia."

On the battlefield, Ukrainian officials said a Russian rocket attack targeted an area around Zaporizhzhia, destroying unspecified infrastructure. There were no immediate reports of casualties. The southeastern city has been a refuge for civilians fleeing the Russian siege in the devastated port city of Mariupol.

Russian forces continued to pound the steel plant that is the last bastion of Ukrainian resistance in Mariupol, as per fighters inside the plant. The Azov Regiment said on social media that Russian forces carried out 38 airstrikes in the previous 24 hours on the grounds of the Azovstal steelworks.

The plant, with its network of tunnels and bunkers, has sheltered hundreds of Ukrainian troops and civilians during a months-long siege. Scores of civilians were evacuated in recent days, but Ukrainian officials said some may still be trapped there.

In his nightly address on Tuesday, President Volodymyr Zelenskyy suggested Ukraine's military is gradually pushing Russian troops away from Kharkiv, the country's second-largest city and a key to Russia's offensive in the Donbas, the eastern industrial region whose capture the Kremlin says is its main objective.

Ukraine is also targeting Russian air defences and resupply vessels on Snake Island in the Black Sea in an effort to disrupt Moscow's efforts to expand its control over the coastline, according to the British Ministry of Defence.

Separately, Ukraine said it shot down a cruise missile targeting the Black Sea port city of Odesa.

(With AP inputs)