US President Donald Trump/SCREENGRAB

US President Donald Trump has announced an immediate energy ceasefire between Russia and Ukraine, but Ukrainian President Volodymyr Zelensky says the declaration was news to him.

Trump claimed both sides had agreed to halt attacks on energy infrastructure, although Russia had yet to comment on the announcement.

“Effective immediately, there is an ENERGY CEASEFIRE in the war between Russia and Ukraine. Both parties have agreed. Do not break it!” Trump wrote on Truth Social.

However, Zelensky told US news site Axios that the announcement had caught him by surprise.

“But if Russians agree to an energy ceasefire, Ukraine will agree,” he said.

A senior official close to Zelensky also reportedly told the Financial Times that neither side had been informed of the proposed truce, saying, "Nobody has heard [of it].”

The announcement came amid rising tensions between Trump and Zelensky over attacks on energy infrastructure as Russia's war against Ukraine continues into its fifth year.

Trump had earlier warned Ukraine to “damn well stop” attacking Russian oil refineries.

On Sunday, Zelensky said Ukraine would be “ready to stop striking Russian oil refineries if Russia stops striking our energy infrastructure”.

Both countries have intensified attacks on critical infrastructure in recent months, with energy facilities among the targets.

Trump's announcement did not provide details on the scope or duration of the proposed ceasefire.

The White House had been approached for clarification, while efforts were underway to obtain a response from the Ukrainian side.