Ukrainian president Volodymyr Zelensky said the country's army was not ready to try to break through the siege of the port city by force. But he told an evening news conference that Kyiv had every right to do so.
The attack on Mariupol has raged for weeks as Russia seeks to capture a city seen as vital to its attempts to link the eastern Donbas region with Crimea, the Black Sea peninsula Moscow seized in 2014. It has been the biggest battle of the conflict so far.
Moscow-backed separatists have held territory in the Donbas region for years.