The seaport of Mariupol in south-eastern Ukraine has been under Russian shelling and besieged for weeks.
Some residents were able to flee in convoys of cars from 16 March, but there are still an estimated 300,000 in the city with no electricity or running water.
Food is scarce and aid shipments have been prevented from entering the city. Ukrainian officials estimate that at least 2,500 civilians in the city have died. Several thousand residents have been forcibly evacuated to Russia.
