Kyiv (Ukraine) (AFP) - Russia agreed Thursday to help residents leave a region it has “annexed” in a new sign Kyiv’s counter-offensive is advancing, as a top EU official warned Moscow’s army would be “annihilated” by the West if the Kremlin uses nuclear weapons in the war.

Russia’s decision came a day after Kyiv said it had retaken five settlements in the southern Kherson region.

“The government took the decision to organise assistance for the departure of residents of the (Kherson) region,” Russian Deputy Prime Minister Marat Khusnullin said.

The Moscow-appointed head of the area in southern Ukraine – which Russia says it has annexed – had appealed for Russian intervention.

Vladimir Saldo suggested residents “leave to other regions to protect themselves from missile strikes”.

Kherson was being hit by an increasing amount of rockets causing “serious damage”, added Saldo, with civilian infrastructure being targeted.

Those departing would go to Crimea, a Ukrainian peninsula Moscow annexed in 2014, and southern Russian regions.

Kyiv, which announced its counter-offensive in the south in August, said it has already recaptured over 400 square kilometres (155 miles) in the Kherson region in under a week.

The city of Kherson, which lies near Crimea, was the first major Ukrainian city to fall to Russian forces after the February 24 invasion.

In Brussels, EU foreign policy chief Josep Borrell sent a strong message to the Kremlin after President Vladimir Putin’s veiled threats of resorting to nuclear weapons to stem growing battlefield losses.

“Putin is saying he is not bluffing. Well, he cannot afford bluffing, and it has to be clear that the people supporting Ukraine and the European Union and the Member States, and the United States and NATO are not bluffing neither,” Borrell said.

“Any nuclear attack against Ukraine will create an answer, not a nuclear answer but such a powerful answer from the military side that the Russian Army will be annihilated,” Borrell added.

The NATO alliance has stopped short of threatening to use its nuclear arsenal to respond as non-member Ukraine is not covered by its mutual self-defence clause.

The United States and NATO have steered clear of intervening militarily in the Ukraine conflict for fear of sparking a catastrophic nuclear conflict with Moscow.

- Booming trade -

In Ankara, President Recep Tayyip Erdogan defended Turkey’s booming trade ties with Moscow during an in-person meeting with Putin on the sidelines of a summit of regional leaders in Kazakhstan.

But Erdogan did not deliver an offer to mediate negotiations between Moscow and Kyiv – expected by the Kremlin.

Comments between the leaders made no mention of Ukraine and focussed instead on economic ties.

Putin proposed to create a “gas hub” in Turkey as Russia’s supplies to Europe have been disrupted by Ukraine-related sanctions.

NATO member Turkey has sought to retain dialogue with its Western allies as well as Moscow, and has not joined sanctions on Russia over its invasion of Ukraine.

Erdogan also refrained from commenting on mass Russian strikes on Ukraine earlier this week that mostly targeted energy infrastructure and left at least 20 dead.

The attacks caused power and hot water cuts across the country, but the head of Ukraine’s energy operator Ukrenergo said Thursday the power grid had “stabilised”, reassuring users emergency power cuts would be unneccessary.

- Rebels push to Bakhmut -

On the battlefield, Russian-backed separatist forces in the eastern Donetsk region of Ukraine said they had captured two villages near the industrial city of Bakhmut, posting small gains against Kyiv’s counter-offensive.

The villages lie just south of Bakhmut, a wine-making and salt-mining city that used to be populated by some 70,000 people and which Russian forces have been pummelling for weeks to capture.

The reported gains came after Ukrainian troops had for weeks been clawing back large swathes of territory in the south and east of Ukraine – including Donetsk – controlled by Russian forces for months.

The Ukrainian military countered in an update that it had repelled attacks near several frontline villages.

- Boy pulled from rubble -

Ukraine troops told AFP this week near the frontline south of Bakhmut that they were still outgunned by Russian artillery on their section of the frontline.

Russian supply lines from the part of Donetsk occupied since 2014 are still intact.

AFP reporters in Yampil just outside the recently liberated town of Lyman on Thursday heard heavy exchanges of artillery fire to the southeast.

A Ukrainian soldier returning from the frontline said positions in Torske village were under fire from Russian guns guided by spotter drones.

Also in the south, the town of Mykolaiv was again rocked by Russian bombardments.

The head of the city Oleksandr Sienkevych said on social media a five-storey residential building was hit, with two upper floors destroyed completely.

“An 11-year-old boy was recovered from under the rubble and another seven people may still be there,” he said, adding a security guard was killed at a sea rescue station.