UK Foreign Secretary Lord Cameron has said it is up to Ukraine to decide how to use British weapons and insisted it has the right to strike targets on Russian territory.

During a visit to Kyiv, he said the UK would provide £3bn ($3.75bn) per year for as long as necessary.

“Just as Russia is striking inside Ukraine, you can quite understand why Ukraine feels the need to make sure it’s defending itself,” Lord Cameron said.

Russia condemned what it called “another very dangerous statement”.

“This is a direct escalation of tension around the Ukrainian conflict, which would potentially pose a threat to European security,” said Kremlin spokesman Dmitry Peskov.

The US has reportedly urged Ukraine to halt its strikes on oil refineries in Russia, fearing it could provoke an escalation in the conflict.

Mr Peskov also took aim at French President Emmanuel Macron, who said this week that the West would “legitimately” have to consider whether to send ground troops to Ukraine “if the Russians were to break through the front lines, if there were a Ukrainian request”.

Mr Macron’s remarks to The Economist were a “very dangerous trend”, said the Kremlin spokesman. However, the French leader made clear in his interview that if Russia won in Ukraine, there would be no security in Europe.

Russian forces have seized several villages in eastern Ukraine during recent advances, taking advantage of Ukraine’s shortages of weapons and manpower.

Ukrainian intelligence officials also believe Russia is gearing up for a summer offensive in the north-eastern regions of Kharkiv and Sumy.

The commander of the national guard, Oleksandr Pivnenko, warned recently that Russia was preparing “unpleasant surprises” and quietly recruiting 30,000 people a month.

A Russian strike on Kharkiv on Friday killed an elderly woman in her home, and a tram carrying passengers also came under fire, according to Mayor Ihor Terekhov.

Ukraine’s military says Russia’s immediate target is the strategic hilltop town of Chasiv Yar, 15km (9 miles) west of the devastated city of Bakhmut.

Officials believe the eastern town could enable Russian forces to attack major eastern cities such as Kramatorsk and Slovyansk. The military has suggested Moscow is keen to seize Chasiv Yar before Russians mark victory in World War Two on 9 May.

However, a Ukrainian military spokesman has denied that Russian troops have broken through to the Siverskyi Donetsk-Donbas canal on the outskirts of the town.

Russia claimed on Friday that its forces had captured three villages in Ukraine’s east in the past two weeks. Military spokesman Lt Col Nazar Voloshyn said the invading force had gained a foothold in the village of Ocheretyne but Ukrainian soldiers were working to drive them out.

Lord Cameron, who met President Volodymr Zelensky in Kyiv, said it was Russia that had launched an attack into Ukraine and Ukraine “absolutely has the right to strike back at Russia”.

Russian Foreign Ministry spokeswoman Maria Zakharova said his remarks were tantamount to admitting the West was involved in a “hybrid war” against Moscow.

The UK has provided billions of pounds in military support for Ukraine since Russia launched its full-scale invasion in February 2022, ranging from tanks and precision-guided missiles to air-defence systems.

A year ago the UK confirmed it had begun supplying long-range Storm Shadow cruise missiles with a range of more than 250km (155 miles).

Meanwhile, Ukrainian Prime Minister Denys Shmyhal said he had appealed to Lord Cameron to help restore the country’s energy infrastructure which has been badly damaged by repeated Russian missile strikes.