Volodymyr Zelensky said his meeting with Donald Trump on the fringes of the Pope’s funeral “has potential to become historic”.
The Ukrainian president and his US counterpart met within St Peter’s Basilica after they each paid respects at Francis’ coffin.
A photograph of the two leaders shows them sat opposite one another on chairs within the great church at the heart of Vatican City.
Prime Minister Sir Keir Starmer and France’s Emmanuel Macron were also pictured alongside the American and Ukrainian presidents in images from the encounter, though details have yet to be released about their involvement.
The US has been pressing Ukraine to accept a peace deal which would require Kyiv to accept Russian control of vast swathes of occupied land.
Mr Zelensky has insisted he will not recognise Russian sovereignty over Crimea, the region occupied by Moscow’s forces since 2014, nor continued Kremlin control in Ukraine’s south and east.
He has called for Vladimir Putin to instead accept an unconditional end to the fighting.
Following the funeral ceremony’s end, the Ukrainian leader said his face-to-face encounter with Mr Trump – their first since a tempestuous clash in the White House in February – had been a “good meeting”.
In a post on social media site X, he added: “We discussed a lot one on one. Hoping for results on everything we covered.
“Protecting lives of our people. Full and unconditional ceasefire. Reliable and lasting peace that will prevent another war from breaking out.
“Very symbolic meeting that has potential to become historic, if we achieve joint results.”
Mr Zelensky’s spokesperson, Serhii Nykyforov, said the meeting lasted around 15 minutes.
Mr Trump was reported to have left Rome soon after the funeral, while the Ukrainian leader was expected to engage in further talks with other leaders.
The Ukrainian leader received a round of applause as he stepped out into St Peter’s Square from the basilica and was noticed by other world leaders.
Elsewhere during the funeral, Mr Trump and Mr Macron shook hands as part of the ceremony.
The leaders made the gesture when the congregation was invited to offer those around them a “sign of peace” – a traditional part of the Roman Catholic mass.
The gathering in Rome offers the UK’s Sir Keir the opportunity to raise continued support for Ukraine, and other issues like US tariffs, with his counterparts from across the globe.
William, the Prince of Wales, is also among the leading dignitaries who attended the ceremony in St Peter’s Square.
The Prince spoke with both the US president and Mr Macron as world leaders gathered ahead of the funeral.
The Prime Minister and Mr Macron are leading efforts to establish a peacekeeping mission that will enforce a possible future ceasefire in Ukraine.
Reports in recent days have suggested British military figures think the so-called coalition of the willing is now too-risky a prospect.
Downing Street has brushed aside these claims, while the Telegraph newspaper has reported the US has privately indicated it is willing to back up European peacekeepers in the face of potential Russian aggression.
As he touched down in Rome on Friday night, Mr Trump called for Ukraine and Russia to meet “at very high levels” as a deal is now “very close” to being agreed.
He has expressed public anger with Mr Zelensky in recent weeks, because of the Ukrainian leader’s insistence he will not cede territory to Moscow to get a peace deal over the line.
By David Lynch, PA Political Correspondent
