Donald Trump has announced an agreement with Vladimir Putin for the US to buy Russian diesel, saying it is needed to bring down fuel prices.

Ukrainian president Volodymyr Zelenskyy condemned Friday’s announcement and warned that dealings with Putin could give Russia more opportunities on the battlefield. The move could also strain relations with Ukraine and Nato allies after years of Western pressure on Moscow over its war against Ukraine.

Trump said on Truth Social that Russia would deliver millions of tonnes of diesel over the coming months. US fuel costs have risen since Iran closed the strait of Hormuz; the price of diesel reached a record $6.52 last month.

Separately, Ukrainian officials reported that a Russian attack in the country’s south-east had killed 12 people, including three children. Moscow claimed its troops were advancing in the east.