"These discussions are not easy, not least in the wake of this horrific violence. But we all support President Trump's push for peace," Rutte said of US-led talks during a surprise visit to the port city of Odesa, where he met with Ukrainian leader Volodymyr Zelensky.

Rutte's comments contrast with an assessment from Trump's special envoy Steve Witkoff, who said he sees a peace deal "emerging" after talks with Russian leader Vladimir Putin in Russia.

Despite a flurry of diplomacy, there has been little meaningful progress on Trump's main aim of achieving a ceasefire in Ukraine.

The Kremlin, which launched its full-scale invasion of Ukraine in February 2022, rejected a US and Ukrainian proposal for an unconditional pause in the fighting last month.

Zelensky meanwhile called for the effective preparation of a contingent of foreign troops to deter Russia from attacking Ukraine again, should a peace deal be secured.

- 'Acute' need for air defences -

"Britain, France and other NATO countries are already actively preparing the ground for a security contingent in Ukraine. It is important that we all be fast enough and efficient in this process," he said.

Zelensky also told Rutte that Ukraine urgently needed air defence systems after recent Russian missile strikes killed dozens of civilians.

"Absolutely everyone sees how acute Ukraine's need for air defence systems and missiles is. We talked about this a lot today," the Ukrainian leader said.

Zelensky's renewed call for more air defence systems comes after recent Russian attacks killed 35 people in north-eastern Sumy region and 19 -- including nine children -- in his hometown of Kryvyi Rig.

The Ukrainian leader earlier said that his country needs 10 more Patriot batteries to defend civilians and infrastructure from Russian attack.

The Ukrainian army meanwhile said it had hit back at a Russian missile unit deployed in the western Kursk region that was responsible for launching Sunday's attack on Sumy.

"Every Russian military unit, subdivision and their servicemen who shell peaceful cities and civilians of Ukraine will be identified and will definitely receive retribution," it said in a statement.

Russian officials earlier in the day said an 85-year-old woman had been killed in a large-scale Ukrainian drone attack.

Ukraine meanwhile said that overnight its air defence systems had downed 26 Russian drones.