Russia declared a partial ceasefire on Saturday to allow humanitarian corridors out of the Ukrainian cities of Mariupol and Volnovakha, Russia's defence ministry said.
"From 10am Moscow time (7am UK time), the Russian side declares a ceasefire and the opening of humanitarian corridors to allow civilians to leave Mariupol and Volnovakha," Russian news agencies quoted the Russian defence ministry as saying.
It comes as the war entered its 10th day on Saturday with Russian troops besieging and bombarding cities in the biggest attack on a European state since World War Two.
The fighting has created over 1 million refugees, a barrage of sanctions that are increasingly isolating Moscow and fears in the West of a wider global conflict that has been unthought-of for decades.
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Moscow says its invasion is a "special operation" to capture individuals it regards as dangerous nationalists, and has denied targeting civilians.
Ukraine's state service of special communications and protection of information says Russian forces have focused efforts on encircling Kyiv and Kharkiv, the second-biggest city, while aiming to establish a land bridge to Crimea.
Kyiv, in the path of a Russian armoured column that has been stalled outside the Ukrainian capital for days, has been under renewed assault, with explosions audible from the city centre.
Russian forces also have encircled and shelled the southeastern port city of Mariupol - a key prize. There is no water, heat or electricity and food is running out, according to Mayor Vadym Boychenko.
"We are simply being destroyed," he said.
President Vladimir Putin's actions have drawn almost universal condemnation, and many countries have imposed heavy sanctions as the West balances punishment with avoiding a widening of the conflict.
Ukrainian President Volodymyr Zelenskiy is expected to press Washington for more help in a Zoom call with the full US Senate at 2.30pm (UK time) on Saturday.
The United States is weighing cuts to imports of Russian oil and ways to minimise the impact on global supplies and consumers as lawmakers fast-track a bill that would ban Russian energy imports.
At a meeting on Friday, NATO allies rejected Ukraine's appeal for no-fly zones, saying they were increasing support but that stepping in directly could make the situation worse.
"We have a responsibility ... to prevent this war from escalating beyond Ukraine because that would be even more dangerous, more devastating and would cause even more human suffering," said NATO Secretary-General Jens Stoltenberg.
