Russia and Ukraine started a major prisoner exchange on Monday after days of wrangling cast doubt over the only concrete result of peace talks last week in Turkey.

Russian officials say that Moscow is still awaiting confirmation from Kyiv on a planned exchange of 6,000 bodies of soldiers killed in action and is accusing Ukraine of delaying the process

Russia and Ukraine on Monday swapped a first group of captured soldiers -- part of an agreement reached during peace talks that appeared to be in doubt over the weekend.

Russia struck Ukraine with a thunderous aerial bombardment overnight, further dampening hopes that the warring sides could reach a peace deal anytime soon.

Since last sitting down with Ukraine to talk peace, Russia has launched four of its five largest drone attacks against the country, killed more than 340 of its civilians and continued to peddle its false narrative about the unprovoked war it has been waging for more than a decade.

It restated Moscow's demands that Ukraine become a neutral country - ruling out membership of NATO - and that it protect the rights of Russian speakers, make Russian an official language and enact a legal ban on glorification of Nazism. Ukraine rejects the Nazi charge as absurd and denies discriminating against Russian speakers.