The 27-nation EU has so far trained over 80,000 Ukrainian soldiers outside the borders of the war-torn country to help it battle Moscow's invasion.

Kallas said the move could be part of broader Western security guarantees given to Ukraine to help shore up any ceasefire agreed with Russian President Vladimir Putin.

"I welcome that there is broad support today to expand our EU military mission mandate to provide training and advice inside Ukraine after any truce," Kallas said after talks with EU defence ministers.

"We must be ready to do more. This could include placing EU trainers in Ukrainian military academies and institutions," she said.

As part of the US-led peace efforts, Western powers are discussing how to guarantee Ukraine's security in case of a truce deal.

President Donald Trump has indicated the United States could play a role backing up a European peacekeeping plan, but would not deploy American soldiers to Ukraine.

Despite Trump throwing his weight into trying to end the war, Moscow continues to stall on a potential meeting between Russian President Vladimir Putin and Ukraine's Volodymyr Zelensky.

In the meantime Moscow has carried out waves of bombardments on Ukraine, including deadly strikes on Kyiv this week.

"The past weeks we have seen diplomatic efforts to end Russia's war, and it's clear that Europe wants peace. America wants peace. Ukraine wants peace," Kallas said.

"Who doesn't want peace is Russia."