The Kremlin says anti-Russia sanctions will have to be reviewed if Moscow is to heed a UN appeal to open Ukraine’s Black Sea ports.

It is estimated by Moscow that some 2,000 Ukrainian soldiers and fighters are holed up inside the plant.

Moscow says the current flow of arms by the West to Kiev impedes a "quick" end to war in Ukraine.

Russia has announced a three-day ceasefire in the besieged Ukrainian port city of Mariupol to allow the evacuation of civilians from a steel plant in the city.

Russian forces have reportedly launched a series of fresh assaults on different sites in eastern Ukraine, as Moscow's offensive against the former Soviet country continues.

The conflict in Ukraine has raised the prospects of an all out confrontation between nuclear armed states with Russian Foreign Minister, Sergei Lavrov, warning of the likelihood of World War III breaking out.

The evacuation of civilians from the Ukrainian city of Mariupol has stalled as Russia's offensive in the east continues.