Live updates: follow the latest news on Russia-Ukraine
Mr Zelenskyy said that if Ukraine possessed arms “comparable to the weapons used by the Russian Federation”, the war would be long over because “the superiority of the Ukrainian military in tactics and wisdom is quite obvious".
He said the Russian military was throwing everything it had at Ukraine, with most of its combat-ready troops concentrated in the country and just across the border in Russia.
“They have driven almost everyone and everything that is capable of fighting us against Ukraine,” Mr Zelenskyy said in his nightly video address to the nation.
And despite Russian claims of hitting only military sites, he said they continued to aim at residential areas and kill civilians.
“The Russian army is blocking any efforts to organise humanitarian corridors and save our people,” Mr Zelenskyy said.
“The occupants are looking to deport or even mobilise the local residents who have fallen into their hands.
“The fate of at least tens of thousands of Mariupol residents who were previously relocated to Russian-controlled territory is unknown.”
“The Russian army in this war is writing itself into world history forever as the most barbaric and inhuman army in the world."
He said the Kremlin has not responded to a proposal to exchange Viktor Medvedchuk, the jailed leader of a pro-Russia party, for the Mariupol defenders.