Rockets hit Kyiv during the UN Secretary General's visit to the city, in which he criticised his own organisation's Security Council, BBC reports.
Antonio Guterres said the council had failed to prevent or end the war in Ukraine.
This was "a source of great disappointment, frustration and anger," he said.
"Let me be very clear:
failed to do everything in its power to prevent and end this war," he added.The 15-member UN Security Council is specifically tasked with ensuring global peace and security.
But it has faced criticism, including from Ukraine's government, for failing to act since the invasion began in February.
Russia is one of five permanent members of the body and it has vetoed more than one resolution on the conflict.
Guterres was speaking on Thursday evening at a joint news conference with Ukrainian President Volodymyr Zelensky, who has previously criticised the Security Council.
"I am here to say to you President, and to the people of Ukraine, we will not give up," he said.
But Guterres also defended his organisation, admitting that while the Security Council had been "paralysed" the UN was taking other actions.
"The UN is the 1,400 staff members in Ukraine who are working to provide assistance, food, cash
other forms of support," he said.
