Ukraine on Tuesday accused Russia of violating a humanitarian corridor aimed at enabling civilians to leave the beleaguered southern port city of Mariupol.
"The enemy has launched an attack heading exactly at the humanitarian corridor," the defense ministry said on Facebook, adding the Russian army "did not let children, women and elderly people leave the city.”
"Such actions are nothing other than a genocide," it added.
Late Monday, Russia named Mariupol as one of four cities where evacuation corridors would be opened.
"Ceasefire violated!" tweeted Ukraine's foreign ministry.
"Russian forces are now shelling the humanitarian corridor from Zaporizhzhia to Mariupol. 8 trucks + 30 buses ready to deliver humanitarian aid to Mariupol and to (evacuate) civilians to Zaporizhzhia," it added.
Kyiv said it had carried out de-mining activities along the 250-kilometer (150-mile) route to Zaporizhzhia in the northwest to allow the evacuation of the roughly 450,000 people living in Mariupol.
The city has been under siege by the Russian army for several days.
It is a key strategic location due to its proximity to the Russia-controlled Crimean peninsula and the Donbas region where Russian separatists are based.
Attempted evacuations involving some 300,000 civilians from Mariupol have failed on several occasions in recent days, with both Kyiv and Moscow blaming the other side for the failures.
Ukrainian President Volodymyr Zelenskiy said there had been "guarantees" on evacuating Mariupol civilians but that these "did not work."