Multiple explosions rocked Ukraine’s capital of Kyiv early on Sunday, Mayor Vitali Klitschko confirmed.

       “Several explosions in Darnytskyi and Dniprovskyi districts of the capital,” Mr Klitschko wrote on the Telegram messaging app, adding, “Services are already working on site. More detailed information - later.”

       A witness for Reuters saw smoke in the city after the explosions.

       Ukraine-based journalist Nika Melkozerova reported “Kyiv is shelled” and that “at least five blasts” were heard near her home in the capital.

       ”It’s been a while since I saw smoke from my window,” her tweet on Sunday read.

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       The Ukrainian city was shelled one day after officials said troops had recaptured a swath of the battlefield city of Sievierodonetsk in a counter-offensive against Russia.

       This claim could not be independently verified, and Moscow said its own forces were making gains there. But it was the first time Kyiv has claimed to have launched a big counter-attack in the small industrial city after days of yielding ground.

       Sievierodonetsk Mayor Oleksandr Stryuk said street fighting continued during the day on Saturday, with both sides exchanging artillery fire.

       “The situation is tense, complicated,” he told national television, saying there was a shortage of food, fuel and medicine.

       “Our military is doing everything it can to drive the enemy out of the city,” he added.

       Russia has concentrated its forces on Sievierodonetsk in recent weeks for one of the biggest ground battles of the war, with Moscow appearing to bet its campaign on capturing one of two eastern provinces it claims on behalf of separatist proxies.

       Serhiy Gaidai, governor of Ukraine’s Luhansk province including Sievierodonetsk, said Ukrainian forces previously in control of just 30 per cent of the city had mounted a counter-attack, recapturing another 20 per cent of it.

       Both sides claim to have inflicted huge casualties in the fighting, a battle that military experts say could determine which side has the momentum for a prolonged war of attrition in coming months.

       Russian president Vladimir Putin will discuss the war in an interview due to be broadcast on national television on Sunday.

       In a brief excerpt aired on Saturday he said Russian antiaircraft forces have shot down dozens of Ukrainian weapons and are “cracking them like nuts”.

       Meanwhile, Ukrainian president Volodymyr Zelenskiy offered a stark message, saying that “the terrible consequences of this war can be stopped at any moment ... if one person in Moscow simply gives the order,” apparently referencing Mr Putin.

       “The fact that there is still no such order is obviously a humiliation for the whole world,” he added

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       Tens of thousands are believed to have died in the invasion, which began in February. Millions have been uprooted from their homes, and the global economy has been disrupted in a war that marked its 100th day on Friday.

       Additional reporting by Reuters