Ukrainian President Volodymyr Zelensky has warned that Russia is preparing to intensify its offensive along his country’s northern border, as the death toll rose to 14 in an aerial bomb attack on a shop in the city of Kharkiv.

The bombing of the large construction supplies store on Saturday afternoon also left 43 injured and 16 missing, Kharkiv’s governor Oleh Syniehubov said.

In a video statement from the city, Mr Zelensky said Russia is preparing offensive action 55 miles north-west of Ukraine’s second largest city.

He did not specify where Russian troops are being assembled, but Ukrainian officials have expressed strong concern about the Sumy region. Both Kharkiv city and Sumy, with about 250,000 people, are within 15 miles of the Russian border.

Aftermath of Russian attack
A street in Kharkiv was left covered with debris after a Russian missile attack on Saturday (Andrii Marienko/AP)

Moscow’s troops have in recent weeks captured villages in the Kharkiv area as part of a broad push, and analysts say they may be trying to get within artillery range of the city.

Ukrainian authorities have evacuated more than 11,000 people from the region since the start of the offensive on May 10.

Russian forces are carrying out offensive attacks across the 620-mile front line, with pitched battles in the Chasiv Yar direction of the Donetsk region, where “the intensity of the hostilities is quite high”, according to a statement from Ukraine’s General Staff.

“The defence forces are taking measures to prevent the advance of the enemy,” the statement said.

Volodymyr Zelensky
Ukraine’s President Volodymyr Zelensky warned of a new Russian offensive (Ukrainian Presidential Press Office/PA)

Russia launched wide missile and drone attacks on much of Ukraine during the night into Sunday. Ukrainian officials said air defence units intercepted 31 Shahed drones and 12 cruise missiles launched by Russia in the Mykolaiv, Odesa, Dnipropetrovsk, Poltava, Zaporizhzhia, Khmelnytskyi, Kirovohrad, Vinnytsia and Chernihiv regions.

In total Russia launched 14 missiles and more than three dozen drones, according to a statement from Ukraine’s air force. It was not clear what damage may have been caused by missiles and drones that were not shot down.

Meanwhile, the governor of Russia’s Belgorod region, which lies across the border from Ukraine, said four people were injured in Ukrainian attacks during the night.

The Russian Defence Ministry said seven drones were shot down over the Kursk region and three over Oryol, both of which are to the north of Belgorod.