US President Donald Trump made a surprise announcement of an energy ceasefire between Russia and Ukraine on Sunday that he said ​was "effective immediately", but Ukrainian leader Volodymyr Zelenskiy said he was still waiting to see details of the deal.

There was no word from Moscow on the announcement, which followed ‌days of intense pressure from Trump for Ukraine to halt its attacks on Russian oil refineries, reported Reuters.

In a ​post on his Truth Social platform on Sunday, Trump unexpectedly announced that Ukraine and Russia had agreed to an energy ceasefire, but did not elaborate further.

"Effective immediately, there is an ENERGY CEASEFIRE in the War between Russia and Ukraine. Both parties have agreed,'' he wrote on his Truth Social network.

In a dramatic deterioration in relations, Trump on Saturday warned Zelenskiy that he had "better damn well stop" attacking Russian refineries, and urged Ukrainians to replace their leader at new elections. Trump said Zelenskiy had missed several opportunities to strike a deal with Moscow.

He blames those strikes for a rise in diesel prices that is hurting his Republican Party ahead of US midterm elections next month.

Meanwhile, the US is threatening to block Ukrainian weapons after Kyiv's deep strikes on Russian oil refineries, the Financial Times reported.

The publication says officials from the US have called European allies to lobby for an end to the attacks on Russia's energy infrastructure.

The message from the States reportedly included threats to cut off intelligence sharing and the Purl (Prioritised Ukraine Requirements List) mechanism for procuring ‌US weapons for Ukraine.

Zelenskiy said in a post on the Telegram app that ​he had discussed Trump's announcement with Nato Secretary General Mark Rutte, Canadian Prime Minister Mark Carney and Finnish President Alexander Stubb.

"Ukraine supports the ceasefire, and it is important that Russia support it as well. We ​are awaiting details from the American side," he said.

British Prime Minister Andy Burnham has said the UK "strongly supports" Trump's call for an energy ceasefire. In a post on X, Burnham said he discussed the matter with Zelenskyy yesterday, reported SkyNews.

"Ukraine is ready if Russia stops its attacks," he wrote. "This is the best route to get energy and fuel back into world markets," he added.

Meanwhile Trump has called for elections in Ukraine, suspended since the 2022 Russian invasion, to which Zelenskiy responded that he ​would call a vote if Putin agreed to a 60-day ceasefire.

Zelenskiy said it was "up to Ukrainians" to choose their leader, but added that there needed to be an end to the fighting first. Ukrainian law prohibits elections under martial ‌law for security ⁠reasons.

An "energy ceasefire" would be a dramatic diplomatic breakthrough ahead of the winter. It remains unclear if Russia indeed agreed to stop the strikes, reported Axios.

Trump had made a similar announcement last month, but neither party confirmed that there was a deal. Both Russia and Ukraine continued attacking energy infrastructure, it stated.

In a short interview after Trump's announcement, Zelensky told Axios, "If President Trump negotiated it with Putin, please tell us when the ceasefire begins. We are ready, and we will accept it."

"Please tell Putin, give us two months, 60 days of total ceasefire, 60 days, and we will organise elections," Zelenskiy said.

The announcement follows days of escalating tensions between Trump and Zelensky over Ukraine's attacks on Russian oil refineries.

The Ukrainian leader rejected that he was to blame for energy price rises, adding that "everybody in the world" knew that the war in the Middle East was a bigger factor.

The steep rise in global diesel prices, which followed the outbreak of the Iran war in February, has become a political liability for Trump's Republican Party ahead of the midterms, when opposition Democrats could gain control of one or both houses of Congress.