Ukrainian President Volodymyr Zelensky on Saturday called on the United States to put more pressure on Russia to end the conflict, as diplomats converged on Miami for fresh talks.

Zelensky also said that Washington had proposed the first face-to-face negotiations between Ukraine and Russia in half a year, but later expressed scepticism that would help.

"America must clearly say: if not diplomacy, then there will be full pressure...Putin does not yet feel the kind of pressure that should exist," he said, stressing the need for more arms supplies to Ukraine and sanctions on the entire Russian economy.

The Ukrainian leader's comments in Kyiv came as Russian envoy Kirill Dmitriev arrived in Miami where Ukrainian and European teams have also gathered for the negotiations, mediated by US special envoy Steve Witkoff and President Donald Trump's son-in-law Jared Kushner.

Trump's envoys have pushed a peace plan in which the United States would offer security guarantees to Ukraine, but Kyiv will likely be expected to surrender some territory, a prospect resented by many Ukrainians.

However, US Secretary of State Marco Rubio on Friday promised not to force Ukraine into any agreement, saying "there's no peace deal unless Ukraine agrees to it."

He added that he may join Saturday's talks in Miami, his hometown.

Earlier Saturday, Zelensky had revealed Washington had proposed negotiations that would include Ukraine, the United States and Russia.

He added that Europeans could be present and it would be "logical to hold such a joint meeting."

But he subsequently told journalists, "I am not sure that anything new could come of it." (AFP)