Around 35,000 Ukrainians were evacuated through humanitarian corridors from three cities on Wednesday, President Volodymyr Zelenskyy said, adding authorities planned to open another six escape routes on Thursday.

Zelenskyy said in a televised address that rescue efforts would focus on Mariupol and Izyum, which have both been heavily bombarded. A children's hospital was bombed in Mariupol on Wednesday despite a Russian pledge to halt firing so at least some trapped civilians could escape the city.

Zelenskyy said the 35,000 civilians had left from the cities of Sumy and Energodar as well as towns in the Kyiv region.

Interfax Ukraine news agency earlier cited Kyrylo Tymoshenko, deputy head of the president's office, as saying a total of around 48,000 Ukrainians had been evacuated through humanitarian corridors so far, most of them from Sumy.