Of the 77 UN personnel, 38 were military, three were police, and 36 were civilian. They came from 41 nations.
In a virtual memorial service, Guterres on Tuesday mourned the deaths of the UN personnel and extended his condolences to their families and loved ones, Xinhua news agency reported.
"It is a sad fact that, due to the nature of our responsibilities, our personnel often have to face perilous situations where crisis, conflict and instability reign. That so many of our colleagues choose to serve where risk prevails is testament to their unstinting commitment to helping the world's most vulnerable people, who rely on us for peace, shelter, food, vaccinations and so much more," said Guterres.
The United Nations was born from the ashes of World War II and has promoted peace and human progress ever since. All around the world, especially in the most fragile contexts, the blue flag of the United Nations symbolizes hope, he said.
"That hope is part of the legacy of the colleagues we mourn today. They paid the ultimate sacrifice so that others could look forward to better days."
He promised to constantly review and improve UN practices related to the safety and care of staff. "Even one death is one too many," he said.
Without brave UN staff in the field, the world organization cannot do what it has been asked to do by member states -- to save succeeding generations from the scourge of war and to pursue better standards of living for all in larger freedom, said Guterres.
"On this solemn occasion, let us honour the memory of our fallen colleagues by recommitting ourselves to the noble cause of promoting peace, prosperity and opportunity for everyone, everywhere, for generations to come."