Ukraine's Chernihiv left without water, heating or electricity

Extensive destruction has left the population of Chernihiv without water, heating or electricity, as Russian troops continue to surround the northern Ukrainian city.

Gas supplies were still partly functional, according to the regional administration on Sunday.

The city's infrastructure had been destroyed by "active fighting" but efforts are under way to repair the damage, administration chief Viacheslav Chaus wrote on Telegram.

Russian troops have surrounded the northern city for some time. A key road from the city, located near the Russian and Belarusian borders, leads to Kiev.

Mayor Vladyslav Atroshenko said the city was "completely devastated" by Russian troops, in comments on Saturday. He said more than 200 civilians have been killed in recent weeks and that more than half of the city's original 285,000 residents had left.

Fighting continued throughout the country, with Russian forces also firing on the Neutron Source nuclear research facility in the eastern city of Kharkiv, according to Ukrainian media reports.

The facility, which had already been damaged in a bombing nearly two weeks ago and cut off from its power supply, was shelled on Saturday, Ukrayinska Pravda reported, citing the state nuclear watchdog.

"Verification of the extent of the damage is impossible due to the uninterrupted fighting in the vicinity of the nuclear facility," the report said.

Ukrainian troops meanwhile launched successful counterattacks around the city of Kharkiv in the country's east, according to the regional military chief.

"We are driving the occupiers back in the direction of the [Russian] border," Oleg Synegubov said on Telegram on Sunday.

He said a residential building was hit during Russian airstrikes on the village of Oskil in the Izium region and a four-person family was killed. This could not be independently verified.

Russian forces are moving to Belarus in order to regroup after the heavy losses sustained in Ukraine, according to a Sunday report from the General Staff of the Ukrainian Armed Forces.

The aim of the troop movement is to "rotate units that have suffered significant losses, strengthen existing groups, replenish food, fuel and ammunition, organize the evacuation of wounded and sick personnel," the report said.

The General Staff also said on Sunday night that Russia's military was preparing for new missile attacks on Ukraine by supplying new projectiles to launch pads in Belarus. It was also not possible to verify this information.

Meanwhile fighting continues for Rubizhne, Severodonetsk and Mariupol in south-eastern Ukraine. The General Staff also said the Russian National Guard was trying to stifle popular resistance in occupied areas in the south.

The Russian armed forces have destroyed a large fuel depot in Ukraine near the western city of Lviv, according to information from Moscow.

The fuel depot had supplied the Ukrainian military in the west of the country and near Kiev, Russian Defence Ministry spokesman Igor Konashenkov said in Moscow on Sunday, confirming information from Ukraine from Saturday.

Rockets fired from aircraft and warships destroyed several military objects in the Lviv and Kiev areas, the Russian major general said.

A fuel depot had been hit, Mayor Andriy Sadovyi said. He spoke of five victims, without giving further details. No civilian infrastructure was hit. According to the Ukrainian Civil Defence, the fire at the fuel depot could only be extinguished after 14 hours on Sunday.

In the western Ukrainian region of Rivne, an oil depot was also destroyed by Russian missile fire on Saturday, according to Ukrainian sources. The devastation in the town of Dubno was extensive, the regional administration announced on Sunday.

A total of 67 military targets were destroyed within 24 hours, Konashenkov said in Moscow. Among them were a military repair facility in Lviv, a warehouse with anti-aircraft missiles 30 kilometres south-west of Kiev and 18 combat drones. The attacks in Ukraine would continue, Konashenkov said.

As with most claims from both sides during the war, it was not immediately possible to independently verify the information.

Pro-Russian separatists in the embattled Luhansk region in eastern Ukraine are planning to hold a referendum on the region's accession to Russia, increasing pressure on Kiev.

Russia's war on Ukraine started when, on February 24, Russian President Vladimir Putin ordered a "special military operation" at the request of the self-proclaimed Luhansk and Donetsk People's Republics - which Russia had just recognized as independent - to protect them from the Ukrainian army.

A possible accession of Luhansk to Russia would likely escalate the situation further. The Russian military claims that more than 90 per cent of the region had been wrested from Ukrainian control.

The Ukrainian Foreign Ministry said that such a vote in Luhansk would not be recognized.

Russia annexed the Ukrainian Black Sea peninsula of Crimea in 2014 after a referendum considered illegal by Ukraine and the European Union.

Meanwhile, after about two weeks of peace negotiations in an online format, the delegations from Ukraine and Russia wanted to meet again in person.

The next meeting was set to take place in Istanbul, the Turkish presidential office said on Sunday evening after a call between Putin and his Turkish counterpart, Recep Tayyip Erdoğan.

Russian delegation leader Vladimir Medinsky had earlier said that a meeting was planned for Tuesday and Wednesday. Ukrainian negotiator Davyd Arakhamia also confirmed that a face-to-face meeting was planned, although he said it would begin on Monday.

Delegations from both countries begun negotiations shortly after the start of the war. After three face-to-face meetings in the border area of Belarus, the talks were held via video link.

Ukrainian Foreign Minister Dmytro Kuleba and his Russian counterpart, Sergei Lavrov, also met in Turkey on March 10. The talks in Antalya did not lead to any significant progress.