CHERNIHIV, Ukraine, Aug 20, 2023 (BSS/AFP) - A Russian missile strike on Ukraine's northern city of Chernihiv killed seven people and wounded 144 on Saturday, President Volodymyr Zelensky said, in what the UN denounced as a "heinous" attack.

The strike came during the Orthodox holiday of the Transfiguration of the Lord, as some attended morning church services in the city.

"It is heinous to attack the main square of a large city, in the morning, while people are out walking, some going to church to celebrate a religious day for many Ukrainians," said Denise Brown, the UN's humanitarian coordinator for Ukraine.

"I condemn this repeated pattern of Russian strikes on populated areas of Ukraine... Attacks directed against civilians or civilian objects are strictly prohibited under international humanitarian law," she added.

Audrey Azoulay, director general of the UN's cultural organisation UNESCO, said she was "appalled" by the attack, in a post on social media.

Ukraine's culture ministry said the centre of Chernihiv, a city with a thousand-year history, is a candidate for nomination to the UNESCO World Heritage List.

The city, 150 kilometres (90 miles) north of Kyiv towards Belarus, had until now been largely spared from major attacks since the first months of Russia's invasion as fierce fighting rages in the east and south.

The Russian army marched through the city when it invaded Ukraine through Belarus in February 2022, before being repelled by Kyiv's forces.

- 'Pain and loss' -

Zelensky said the dead included "a girl, her name was Sofia, she was six years old," and that there were 15 children among the 144 wounded.

"Our soldiers will respond to Russia for this terrorist attack -- a tangible answer," he vowed.

From a hospital bed, her legs still covered in blood, Diana Kazakova said she had been inside a shop when the strike happened just minutes after sirens sounded.

When she came to, she said "people were crying, shouting" in the street outside. "It was scary."

Iryna, a 24-year-old bartender in Chernihiv, told AFP: "There was smoke, screams, people were running, crying, moaning. We ran to the shelter when everything happened and sat there."

Zelensky was in Sweden for talks with Prime Minister Ulf Kristersson, where he finalised "the production of CV90 (armoured vehicles) in our country."

"Everything powerful that serves us now, we must localise and produce. We will do so."

They also discussed Ukraine pilots participating in test trials of Swedish Gripen fighter jets, he said in his evening address.

- Putin meets military top brass -

Hours earlier, the Kremlin said Putin had travelled to the southern Russian city of Rostov-on-Don, Moscow's hub for its operations in Ukraine, to meet his top generals in a rare trip close to combat zones.

Moscow gave no details of when the meeting took place, but footage released by state media indicated it was at night.

Putin listened to briefings by the Chief of Staff Valery Gerasimov "and other senior officers of the group", the Kremlin said.

A video published by the RIA Novosti news agency showed Putin, wearing a suit, stepping out of a jeep in the dark and being greeted with a handshake by Gerasimov, in military attire.

Gerasimov is seen leading Putin down a corridor decorated with portraits of Russian military men and of the president chairing a meeting with army chiefs.

Rostov-on-Don was also the scene of a dramatic armed mutiny by Wagner mercenaries in June, which saw them briefly take over the army HQ in Rostov, before halting their rebellion.

Gerasimov, who Wagner wanted to unseat, has rarely been seen in public since.

- Drone attacks -

Kyiv said it had shot down more than a dozen Russian drones in an overnight attack.

And the Russian army said it had thwarted Ukrainian attacks on Crimea as well as attempted drone strikes on a military airfield in the northwestern Novgorod region, Moscow and its region.

A day earlier, Russian forces destroyed Ukrainian drones targeting Moscow and the Black Sea Fleet.

Both sides have reported regular drone incursions as Ukraine presses a counteroffensive to reclaim Russian-held territory.

Russia's army also said it had "eliminated" 150 Ukrainian troops that tried to cross the Dnipro River into Russian-occupied territory in southern Ukraine, a day after admitting sabotage groups were operating in the area.

Ukraine's Foreign Minister Dmytro Kuleba, in an interview with Germany's Bild newspaper, had a dig at pundits who had predicted a swift Russian victory when their troops invaded last year.

Asked about claims the counteroffensive could fail, he said: "We take such statements calmly.

"According to unnamed officials, generals and analysts, Ukraine should have ceased to exist within three to 10 days in February 2022.

"They now assume that Ukraine will not be able to retake all of its territory so quickly. This shows that even doubters are becoming more hopeful with time," he added.