President Donald Trump has signed an executive order suspending US sanctions and tariffs aimed at Russia's energy revenues, effectively shielding Moscow from measures passed by Congress that he himself signed into law last month.

"In accordance with Section 4 of this order, I have decided to suspend the application of the sanctions, restrictions and tariffs provided for in the Graham Act," the order states.

The legislation, named after Senator Lindsey Graham, gave the president authority to impose tariffs of up to 100 percent on major buyers of Russian oil and gas. It targets Russia's energy and defense sectors, President Vladimir Putin and other senior officials, as well as the so-called "shadow fleet" of Russian oil tankers used to circumvent Western sanctions.

The move follows an agreement between Trump and Putin to resume Russian diesel exports in return for an easing of US sanctions on Moscow.

The deal has angered Ukrainian President Volodymyr Zelensky, who described it as a "weak decision." Kyiv has decided to resume strikes on Russian oil refineries, in defiance of what the US president had announced.

The suspension marks a sharp turn for a law designed to squeeze the revenues that fund Russia's war effort, and it leaves Washington and Kyiv at odds over how to handle Moscow's energy sector.