A six-year-old girl has died from dehydration under the rubble of her destroyed home in the besieged Ukrainian city of Mariupol, the city council said Tuesday.

Mariupol is surrounded by Russian forces, who have bombarded the port city despite promises of a ceasefire to allow civilians to be evacuated.

It is not known how long the girl, named only as

Ukraine on Tuesday accused Russia of violating a humanitarian corridor aimed at enabling civilians to leave the beleaguered southern port city of Mariupol.

"The enemy has launched an attack heading exactly at the humanitarian corridor," the defense ministry said on Facebook, adding the Russian army "did not let children, women and elderly people

Desperate civilians fled besieged Ukrainian cities on Tuesday after Russia offered "humanitarian corridors," as the number of refugees leaving the country since Moscow's invasion passed 2 million.

Civilians boarded buses out of the north-eastern city of Sumy, where 21 people were killed in air strikes overnight, while others took an unofficial

Jailed Kremlin critic Alexei Navalny on Tuesday urged Russians to continue protesting against Moscow's invasion of Ukraine, days after thousands of protesters were arrested at anti-war rallies nationwide.

More than 13,500 Russians have been detained at demonstrations against the invasion of Ukraine since President Vladimir Putin ordered his army to