Ukraine clings to Bakhmut, Russia battles 'saboteurs'

Ukrainian have forces hung on to positions in the ruined eastern city of Bakhmut, while Moscow says its security forces are battling Ukrainian saboteurs who had taken hostages in a cross-border raid.

Moscow said a group of armed Ukrainians had crossed into Russia's Bryansk province, fired on a car killing a civilian, and were holding hostages in a shop near the border.

An aide to Ukrainian president Volodymyr Zelenskiy called the reports a provocation by Moscow, but also implied some form of attack had indeed been carried out, blaming Russian partisans.

Near the front lines west of Bakhmut, in the Ukrainian-held town of Chasiv Yar, Reuters heard the thump of outgoing artillery fire on Thursday morning.

In nearby towns and villages, fresh trenches had been dug on the roadside 20-40 metres apart, an apparent sign that Ukrainian forces were strengthening their defensive positions west of the city.

Bakhmut itself has been reduced to a blasted wasteland, with a few thousand of its 70,000 pre-war civilian population still living inside as armies battle street-by-street.

Russian troops, bolstered by hundreds of thousands of reservists called up last year, have been advancing north and south of the city, trying to cut off the remaining routes in and out to the west used by the Ukrainian garrison.

Moscow, which lost territory throughout the second half of 2022, says taking Bakhmut would be a step towards seizing the rest of the surrounding Donbas region a major aim.

Kyiv says the city has limited strategic value, but it is determined to hold it to exhaust Russia's invasion force in what has become the bloodiest battle of the war.

"Sooner or later, we will probably have to leave Bakhmut. There is no sense in holding it at any cost," Ukrainian member of parliament Serhiy Rakhmanin said on Wednesday.

"But for the moment, Bakhmut will be defended with several aims: firstly, to inflict as many Russian losses as possible."

Russia said an armed group of Ukrainians had crossed the border into the Bryansk region to carry out what the Kremlin described as a terrorist attack.

"Today, a Ukrainian sabotage and reconnaissance group penetrated the Klimovsky district in the village of Lubechanye," Bryansk governor Alexander Bogomaz said on Telegram.

"Saboteurs fired on a moving car. As a result of the attack, one resident was killed and a 10-year-old child was wounded."

Russia's RIA state news agency said several people had been taken hostage in a store in Lubechanye, less than a kilometre from Russia's border with Ukraine.

Zelenskiy aide Mykhailo Podolyak called the Russian reports "a classic deliberate provocation".

Moscow "wants to scare its people to justify the attack on another country & the growing poverty after the year of war", he tweeted. But he also implied an attack was indeed under way, carried out by partisans within Russia: "Fear your partisans," he wrote.

Moscow has accused Ukraine of staging a series of drone attacks on targets deep within Russia this week.

Elsewhere, Russian missiles crashed into an apartment block in the southern city of Zaporizhzia overnight, killing three people and wounding at least four,.

Russian forces are under pressure to secure advances now before warmer weather brings the region's season of sucking black mud, which is legendary in military history for destroying armies attempting to attack across Ukraine and western Russia.

Kyiv, for its part, is focusing on defence for now, planning a counteroffensive later this year to recapture the nearly one-fifth of the country occupied by Russian troops.

Apart from the vicinity of Bakhmut, Russia has achieved little in its winter offensive, with notable costly failures, especially to the south at Vuhledar.

The war has dominated a foreign ministers' meeting in New Delhi of the G20, one of the last international forums involving top Western officials where Russia is still invited.

US and European delegates are pushing for a statement that will contain condemnation of the war.