An elderly woman is coated in snow after being evacuated from Irpin, Kyiv, Ukraine, on Tuesday. AP

Vereshchuk said Moscow vowed to respect the truce from 9am to 9pm around six areas that have been heavily hit by fighting, including regions around Kyiv, in Zaporizhzhia in the south, and some parts of Ukraine's northeast.

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Civilians in areas around the capital, including Irpin and Bucha to the northwest, will be evacuated into Kyiv to escape fierce bombardment by Russian forces.

Evacuees stand under a destroyed bridge as they flee the city of Irpin, Kyiv. AFP

Civilians have been braving shellfire and aerial bombardments to escape the cluster of towns on Kyiv's northwestern edge, which have been largely occupied by Russian forces.

An exploding shell killed four people who were trying to reach Kyiv by foot on Sunday.

On Tuesday, some 60 buses in two convoys were able to evacuate civilians out of Sumy, 350 kilometres (220 miles) east of Kyiv, Kyrylo Timoshenko of the Ukraine president's office told local media.

More than 5,000 people were evacuated from Sumy, a town of 250,000 that lies close to the Russian border and has been the scene of heavy fighting.

The UN refugee agency UNHCR has estimated the total number of refugees at 2.1 to 2.2 million.

Agence France-Presse