Russia launched deadly strikes on civilians in Ukraine as “thanks” for a deal cut by Donald Trump with Vladimir Putin to buy large quantities of Russian diesel, Volodymyr Zelenskyy has said, accusing Washington of helping fund Moscow’s war.

The Ukrainian president has expressed repeated outrage at the agreement announced by Trump on Friday, which the US president said was needed to reduce diesel prices, and comes ahead of November midterm elections where the cost of fuel is a key voter issue.

The deal, which appeared to blindside Kyiv as it was announced while Ukrainian negotiators were in Miami for peace talks, was described by Zelenskyy as a “gift” to Russia’s president.

He said Russia would use the money it raised from the fuel sales to invest in its war and that “any easing of sanctions” would play into Russia’s hands, “allowing it to kill more, wage war for longer”.

That prediction was realised hours later, when Ukrainian officials announced that a barrage of Russian strikes on the country’s south-east early on Saturday had killed 15 people, including three children.

“Today, Russia expressed its thanks for the lifting of sanctions on diesel exports by dropping five glide bombs on residential buildings in Zaporizhzhia,” Zelenskyy said on social media on Saturday.

“Last night confirmed once again that in Russia, they take any easing of pressure to mean they can keep fighting, to mean they can keep dropping bombs on cities. Different signals are needed,” he said.

There were also “large-scale power outages” in the capital, Kyiv, the country’s largest private energy provider said.

In stark contrast to Zelenskyy’s open frustration with Trump, a Kremlin readout of Friday’s call between the US president and Putin was glowing, with the Russian ⁠news agency Interfax ⁠quoting ​an aide as saying it was “very substantive and friendly”.

“Neither wanted to be the first to hang up,” the Kremlin foreign policy aide Yuri Ushakov said of the two leaders. “They hung up simultaneously, literally at the same time.” ​Zelenskyy has previously said Putin is playing games with Trump.

The diesel deal disrupts four years of western financial pressure on Moscow and leaves Kyiv’s allies in Europe and Nato scrambling to adapt their sanctions plan. The EU’s top diplomat, Kaja Kallas, said the diesel deal “provides Moscow with more revenues to wage war”.

“This is not the time to ease pressure on Russia, and Europe won’t,” she said on Saturday. “On Monday, EU foreign ministers intend to approve the biggest set of sanctions listings targeting Russia’s war machine since the start of the war.” She was referring to plans to formally add 1,600 new individuals and entities to the EU’s sanctions blacklist.

Major European governments have attempted to balance their diplomatic and trade relationship with a mercurial Trump and their support for Ukraine.

The German government spokesperson Stefan Kornelius said Berlin “remains committed to the sanctions imposed on Russia and is working with its European partners on further sanctions”, adding that support for Ukraine “remains unwavering”.

Ulf Kristersson, the Swedish prime minister, expressed “regret” at the US agreement, saying energy revenues were “a vital source of funding Russia’s war of aggression”.

Zelenskyy said on Saturday that Russia “must feel its losses” and has promised to respond. In the Russian-occupied ‌Luhansk ‌region, Ukrainian attacks in the past 24 hours had killed four ⁠civilians and wounded ⁠five, the region’s ‌Russian-installed governor, Leonid Pasechnik, said ​on Saturday.

Zelenskyy said that Ukraine was ready to take “de-escalatory steps” in the war but only if Russia did the same.

Russia’s fuel production has become a key point of contention between Zelenskyy and Trump, who has attempted to stop Ukraine from bombing Russian refineries, which he says exacerbates a global diesel shortage. The Ukrainian leader has rejected such requests unless Russia stops attacking Ukraine’s energy infrastructure.

The Financial Times reported that during the talks in Miami, Trump’s envoys Steve Witkoff and Jared Kushner raised the possibility that US intelligence sharing could be cut off if Kyiv did not halt the strikes.