On Saturday, Zelensky announced that 307 Ukrainian prisoners had returned home as part of an exchange deal with the Kremlin.
On Friday, Ukraine and Russia each handed over 390 soldiers and civilians in the biggest prisoner exchange since Russia launched its full-scale assault in February 2022.
The two countries have agreed to swap a total of 1,000 prisoners each, and another exchange is expected on Sunday.
US President Donald Trump, who has pledged but so far failed to end the war, suggested on social media that the swap "could lead to something big???".
Earlier this week, Trump had a phone call with Russian President Vladimir Putin about the war, after which he said the Kremlin and Ukraine would "immediately start" negotiations for a ceasefire.
However, Putin has only said Russia would work with Ukraine to craft a "memorandum on a possible future peace agreement", and failed to address calls for a 30-day ceasefire.
