The UN secretary-general has not yet tried to contact Russia's president since the start of the war in Ukraine on February 24, according to Russian Foreign Ministry spokeswoman Maria Zakharova.

"No one has been in touch, neither through Russia's permanent mission to the UN nor through the Foreign Ministry," the official stressed Tuesday.

Russia's Defense Ministry today issued an ultimatum demanding that nationalist battalions and foreign mercenaries in Azovstal "cease any hostility and lay down their weapons" to "ensure the preservation of life" by 12:00 Moscow time.

"Once again, we ask the official authorities to show prudence, to give appropriate instructions to the militants about ending the senseless resistance and leaving the focus of the resistance," writes CNN Portugal.

The industrial park of Azovstal - where a factory was bombed today - is the last stronghold of Ukrainian resistance in the port city of Mariupol. It should also be noted that Russian-backed separatist forces are reportedly trying to storm the Azovstal factory. The last Ukrainian troops in Mariupol are believed to be hiding in the steel mill.