The United Nations needs safe passage to deliver humanitarian aid to conflict zones in Ukraine, a senior official with the organization told the Security Council on Monday.
"Civilians in places like Mariupol, Kharkiv, Melitopol and elsewhere desperately need aid, especially life-saving medical supplies," undersecretary-general for humanitarian affairs Martin Griffiths told an emergency meeting on the disaster sparked by Russia's invasion.
"Many modalities are possible, but it must take place in line with the parties' obligations under the laws of war," he added.
The meeting came as Ukraine and Russia seek an agreement on creating "humanitarian corridors" out of pummeled cities, as the civilian toll from the Russian assault mounts.
Russia said it would open up humanitarian corridors on Tuesday from 0700 GMT, listing evacuation routes from Kyiv as well as Mariupol, Kharkiv and Sumy — all of which have been under heavy Russian attack in recent days.
Ukraine had rejected an earlier Russian proposal for humanitarian corridors from those cities, as many of the routes led straight into Russia or its ally Belarus.
Griffiths urged all sides to ensure that the general population and civilian homes and infrastructure are safeguarded during military operations in Ukraine.
"This includes allowing safe passage for civilians to leave areas of active hostilities on a voluntary basis, in the direction they choose," he said.
The UN also urgently needs a system of "constant communication" with all sides, he said, as well as "assurances to enable the delivery of humanitarian aid."
Griffiths said the UN had sent a team to Moscow for a first technical meeting at the Russian defense ministry.
The goal, he said, is to work on better humanitarian civil-military coordination to be able to "scale up" UN operations, he added.
A senior UN official, speaking on condition of anonymity, said officials also hoped to avoid the possibility of a "blunder" and to ensure that humanitarian convoys were not targeted by Russian attacks.
To date, the UN has had no involvement in the establishment of humanitarian corridors.
Addressing the Council, Linda Thomas-Greenfield, the US ambassador to the United Nations, slammed Russia's attack on Ukraine.
"The humanitarian toll of President Putin's war on Ukraine is mounting. Children are dying, people are fleeing their homes — for what?" she told the meeting.
"Dozens of children have been killed in Putin's war, she said, noting that "actual numbers are likely far greater."
Thomas-Greenfield warned that young children were being "severely traumatized" by the violence and destruction to the point of no longer speaking — and that the physical and psychological wounds of the conflict would be long lasting.
"It's clear Mr. Putin has a plan to brutalize Ukraine," she said.