"Over 12 million people are estimated to be stranded in affected areas or unable to leave due to heightened security risks, destruction of bridges and roads, as well as lack of resources or information on where to find safety and accommodation," the UN said in Friday's statement.
(on to say)
She said humanitarian conditions in Kyiv and Kharkiv are worsening, though they are not yet as bad as they are in Mariupol.
"The humanitarian situation in cities such as Mariupol and Sumy is extremely dire, with residents facing critical and potentially fatal shortages of food, water and medicines," the UN said on Thursday.