Economy minister Yulia Svyrydenko will become prime minister, Zelensky said, while incumbent prime minister Denys Shmygal is expected to replace defence minister Rustem Umerov.

The shakeup, the biggest since the war began, comes after months of setbacks for Ukraine on the battlefield and escalating Russian aerial attacks on Ukrainian cities.

"I have proposed that Yulia Svyrydenko lead the government of Ukraine and significantly renew its work," Zelensky wrote on social media.

"I look forward to the presentation of the new government's action plan in the near future," he added.

In a later evening address, Zelensky announced Shmygal would become defence minister.

"Denys Shmygal's vast experience will certainly be useful in the position of Minister of Defence of Ukraine," he added later, without providing further detail.

Svyrydenko, 39, gained prominence this year for helping broker a minerals deal with the United States that nearly derailed ties between Kyiv and its most important military ally.

Shmygal, 49, had served as prime minister since 2020, steering the Ukrainian government through the COVID-19 pandemic and the start of Russia's full-scale invasion in 2022.

- 'People are exhausted' -

Shortly after Zelensky's announcement, Svyrydenko said Ukraine faced a "crucial time" and listed her priorities as "strengthening" Ukraine's economy, expanding domestic support programmes and scaling up weapons production.

Ukraine's economy has been decimated by the Russian invasion, and Kyiv is reliant on tens of billions of dollars in annual support from Western countries to stay afloat.

Both cabinet appointments will require approval by parliament, which has largely coalesced around Zelensky since the invasion and is unlikely to vote against him.

"The government needs a change because people are exhausted," said Tymofiy Mylovanov, a former economy minister who worked with Svyrydenko.

Mylovanov, who now heads the Kyiv School of Economics, said the changes would likely bring "a sort of freshness" after three and a half years of war.

Zelensky said last week he was also considering naming Defence Minister Rustem Umerov as Ukraine's ambassador to Washington.

Zelensky met with Umerov over the weekend, after which he said that "Ukraine needs more positive dynamics in relations with the United States and at the same time new steps in managing the defence sector of our state."

The appointments come at a pivotal moment in the three-year conflict.

Direct peace talks between Russia and Ukraine on ending the fighting have stalled, while the United States announced earlier that it would boost military support for Kyiv in a major about-turn.