Russia’s UN ambassador has accused the West of being prepared to sacrifice Ukraine and the developing world in order to beat Russia and maintain global power.

"The Ukrainian gang of drug addicts must understand that such attacks will be met with inevitable retaliation using weapons of any kind," Dmitry Medvedev said.

Ukrainian presidential adviser tenders his resignation after a public outcry erupted over comments he made suggesting that Ukrainian forces downed a Russian missile that fell on an apartment building in the central city of Dnipro and killed dozens of people.

Russia and Ukraine have carried out a high-profile prisoner swap, involving almost 300 people, including 10 foreigners, marking the largest exchange since the start of the Ukrainian conflict.

The United States has approved an additional $675 million in weapons to Ukraine.

Putin made the remarks in a video conference with the Russian government figures.

Russia says two Americans captured while fighting with Ukraine's military were "mercenaries" engaged in illegal activities and should be "held accountable for those crimes".